Transfer material method for producing the same and wiring substrate produced by using the same

ABSTRACT

A transfer material capable of transferring a fine wiring pattern to a substrate reliably and easily. The transfer material includes at least three layers of a first metal layer as a carrier, a second metal layer that is transferred to the substrate as a wiring pattern, and a peel layer adhering the first and second metal layers releasably. On the surface portion of the first metal layer, a concave and convex portion corresponding to the wiring pattern is formed, and the peel layer and the second metal layer are formed on a region of the convex portions.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a transfer material fortransferring a fine wiring pattern or circuit components to a substrate,and a method for producing the same. Furthermore, the present inventionrelates to a wiring substrate on which a wiring pattern or a circuitcomponent is formed and a method for producing the same.

[0003] 2. Related Background Art

[0004] Recently, with a demand for high performance and miniaturizationof electronic equipment, high-density and high-performance semiconductordevices increasingly have been desired. This leads to a demand for asmall size and high density circuit substrate on which suchsemiconductor devices are to be mounted.

[0005] In order to meet such demands, a connection method using innervia holes (IVHs) that can connect between wiring patterns of large-scaleintegrated circuits (LSIs) or circuit components in the shortestdistance has been developed in various fields. In general, an example ofwiring patterns having such IVH configurations includes a multi-layeredceramic wiring substrate, a multi-layered wiring substrate produced by abuild-up method, a multi-layered composite wiring substrate including amixture of a resin and an inorganic filler, and the like.

[0006] The multi-layered ceramic wiring substrate can be produced, forexample, by a following method. First, a plurality of green sheetsincluding a ceramic powder such as alumina, etc., an organic binder anda plasticizer are prepared. Then, each of the green sheets is providedwith via holes and the via holes are filled with a conductive paste.Thereafter, a wiring pattern is printed on the green sheets, and theprinted green sheets are laminated. Then, the thus obtained laminate issubjected to a binder removing treatment and a firing treatment, thusforming a multi-layered ceramic wiring substrate. Since the thusobtained multi-layered ceramic wiring substrate has an IVH structure, anextremely high-density wiring pattern can be formed. Therefore, suchmulti-layered ceramic wiring substrates are suitable for miniaturizationof electronic equipment.

[0007] Also, the print wiring substrate produced by the build-up method,which imitates the structure of the multi-layered ceramic wiringsubstrate, has been developed in various fields. For example, JP9(1997)-116267A, JP9 (1997)-51168A, etc. disclose a conventional generalbuild-up method. In this method, a conventionally used glass-epoxysubstrate is used as a core and a photosensitive insulating layer isformed on the surface of the substrate. The surface is provided with viaholes by photolithography, the entire surface is copper-plated, and thenthe copper-plated surface is subjected to a chemical etching process, tothus form a wiring pattern.

[0008] Furthermore, JP9 (1997)-326562A discloses a method in which aconductive paste is filled in via holes processed by photolithography asin the build-up method. JP9 (1997)-36551A, JP10 (1998)-51139A, etc.disclose a method for producing a multi-layered substrate by forming aconductive circuit on one surface of a hard insulating base material andan adhesive layer on another, respectively; providing through holesthereon; filling the through holes with a conductive paste; and thenlaminating a plurality of base materials to thus form a multi-layeredsubstrate.

[0009] Furthermore, specification of Japanese Patent Nos. 2601128,2603053, 2587596 disclose a method for producing a multi-layeredstructure in which an aramid-epoxy prepreg is provided with throughholes by laser machining, the through holes are filled with a conductivepaste, and then a copper foil is laminated and patterning is carriedout. This substrate is used as a core, and is impregnated by prepregswith a conductive paste, to thus form a multilayer structure.

[0010] As mentioned above, similar to the above-mentioned multi-layerceramic wiring pattern, the connection method using IVHs for, forexample, a resin based printing wiring substrate, allows an electricalconnection only between the layers necessary to be connected.Furthermore, since no through holes are provided on the top layer of thesubstrate, the mountability is also excellent.

[0011] However, in general, such a high-density mounted resin basedprinting wiring substrate including an IVH structure has a low thermalconductivity. As the mounting density of components becomes higher, itis getting more difficult to release heat that has been generated in thecomponents.

[0012] In addition, in the year 2000, a clock frequency of a CPU isabout 1 GHz. It is estimated that with the sophistication in thefunction of the CPU, its electric power consumption accordingly reaches100 to 150 W per chip.

[0013] In general, a ceramic wiring substrate excellent in the thermalconductivity has an excellent heat releasing property, but there aresome disadvantages, for example, it is relatively expensive, it is poorin impact resistance property when it is applicable for a substrate or amodule used for portable terminals, and the like.

[0014] Therefore, in order to solve the problem of the thermalconductivity of the resin based printing wiring substrate, or in orderto form a capacitor on the resin multi-layered substrate, a structure inwhich a resin based wiring substrate and a ceramic substrate arelaminated is proposed in specification of Japanese Patent No. 3063427 orJP7 (1995)-142867.

[0015] Furthermore, a multi-layered composite wiring substrate forenhancing the thermal conductivity of a base material itself isdisclosed in JP9 (1997)-270584A, JP8 (1996)-125291A, JP8 (1996)-288596A,JP10 (1998)-173097A, etc. This multi-layered composite substrate isformed by mixing a thermosetting resin such as an epoxy resin and aninorganic filler having an excellent thermal conductivity (for example,a ceramic powder, etc.) to make a composite. This substrate can containan inorganic filler with high density, so that the thermal conductivitycan be enhanced. Furthermore, by selecting a suitable inorganic filler,for example, the dielectric constant, the coefficient of thermalexpansion, or the like, can be controlled suitably.

[0016] On the other hand, in developing the high density mounting of thesubstrate, the formation of a fine wiring pattern is important. Agenerally used method for forming the wiring pattern in themulti-layered ceramic wiring substrate includes, for example, a screenprinting of a thick film conductive paste onto the ceramic substratefollowed by firing for hardening. However, in this screen printingmethod, it is said that the mass production of wiring patterns having aline width of 100 μm or less is difficult.

[0017] Furthermore, in a usual printing wiring substrate, for example, awiring pattern is formed by a subtractive method. In this subtractivemethod, the wiring pattern is formed by chemically etching a copper foilhaving a thickness of about 18 to 35 μm. Also in this case, it is saidthat the mass production of the wiring patterns having a line width of75 μm or less is difficult. In order to make the wiring pattern finer,the copper foil is required to be thin.

[0018] Furthermore, in the subtractive method, since the wiring patternis projected to the surface of the substrate, it is difficult to mount asolder or conductive adhesives, etc. for an electric connection on thebump formed on a semiconductor device. Furthermore, the bump moves to aplace between the wiring patterns, which may lead to a short circuit.Furthermore, the projected wiring patterns may damage the sealing with asealing resin in a later process.

[0019] In addition, in the printing wiring pattern by the build-upmethod, besides the subtractive method, an additive method tends to beemployed. By the additive method, wiring patterns are plated selectivelyon the surface of a substrate on which resist is formed. This allows theformation of wiring patterns having a line width of about 30 μm.However, the additive method has a problem in that the adhesive strengthof the wiring patterns to the substrate is lower as compared with thesubtractive method.

[0020] A method is proposed in which fine wiring patterns that have beenformed beforehand are subjected to a pattern test, and only excellentwiring patterns are transferred to the desired substrate. For example,U.S. Pat. No. 5,407,511 discloses a method in which a fine wiringpattern that has been formed beforehand on the surface of a carbon plateis formed by printing or firing, and then transferred to a ceramicsubstrate. Furthermore, JP10(1998)-84186A, and JP10(1998)-41611 disclosea method of transferring a copper foil wiring pattern that has beenformed on a mold release support plate to a prepreg. Similarly,JP11(1999)-261219A discloses a method of transferring a copper foilwiring pattern to the mold release support plate formed of a copper foilvia a peel layer made of nickel-phosphorus alloy. Furthermore,JP8(1996)-330709A discloses a method of transferring a copper foilwiring pattern to a substrate by utilizing a difference in adhesivedegree between a roughened surface and a bright surface.

[0021] In the wiring patterns transferred by such transferring methods,a wiring pattern is embedded in the surface of the substrate, so thatthe substrate surface becomes flat and can avoid the problem due to theprojection of the wiring pattern. Furthermore, JP10(1998)-190191Adiscloses an effect of compressing a conductive via paste to be filledin through holes by an amount of the thickness of the wiring patternwhen the wiring pattern is embedded in the surface of the substrate.

[0022] In recent years, a further fining of the wiring pattern isdemanded. However, it is difficult to form a finer wiring pattern on themold release support plate by conventional techniques for transferringthe wiring pattern. Namely, for example, when a copper foil adhered tothe mold release support plate is formed into a pattern, if the adhesivestrength of the copper foil with respect to the mold release supportplate is weak, the fine wiring pattern is peeled off in a chemicaletching process. On the contrary, in a case where the adhesive strengthis strong, after the transfer of the wiring pattern to the substrate,when the mold release support plate is peeled off, the wiring pattern ispeeled off together. Furthermore, there is also a method in which thesurface of the copper foil is roughened so as to make the adhesivestrength between the copper foil and the substrate stronger than theadhesive strength between the copper foil and the release moldingsupport plate, thereby transferring the copper foil onto the substrate.However, with this method, it is difficult to form a fine wiringpattern.

[0023] Furthermore, in sintering the conductive paste containing aconductive powder, unlike a metal layer such as a copper foil, theelectric conductivity is poor, which may lead to a problem about a trendtoward a high frequency in the future.

[0024] On the contrary, conventionally, it was difficult to form aceramic multi-layered substrate in which a wiring pattern is formed of ametal foil such as a copper foil, etc. because the formation of a wiringpattern by the use of a metal foil on a green sheet without damaging theproperty of the green sheet is difficult.

[0025] Furthermore, in a production method of the resin based printingwiring pattern, conventionally, a general method is to laminate layerssequentially. A plurality of press processes are needed. Therefore, inorder to realize an accurate interlayer connection, complicated stepsfor correcting hardening and shrinkage occurring in each press processcannot be avoided.

[0026] Furthermore, for the purpose of solving the problem of thethermal conductivity of the resin printing wiring substrate, or forforming a capacitor with a capacitance on the resin multi-layeredsubstrate, a laminated structure itself of a resin printing wiringsubstrate and a ceramic substrate has been proposed. However, in fact,since damages such as cracks are generated mainly in the ceramic layerthrough the laminating process etc., it was difficult to realize thisstructure.

SUMMARY OF THE INVENTION

[0027] It is an object of the present invention to provide a wiringpattern formation and transfer material, which transfers a fine wiringpattern to a substrate, more particularly, to a wiring pattern formationand transfer material capable of transferring a fine wiring pattern to asubstrate easily and reliably and at a low cost.

[0028] In addition, in order to advance the high density mounting, it isimportant not only to make a wiring pattern to be fine but also to formand mount circuit components connecting to a wiring pattern.Conventionally, a passive component such as an inductor, a capacitor, aresistor, or the like, is mounted generally on the surface of thesubstrate. And it was difficult to incorporate such passive componentsinto the substrate. Therefore, there was a limitation to high densitymounting.

[0029] For example, in the conventional method disclosed in theabove-mentioned official gazettes, etc., the pattern formed on thetransfer material is only a wiring portion such as a copper foil. Inorder to enhance the mounting density, a method of mounting the passivecomponents in a form of a chip can be proposed. However, in embeddingthe passive components, etc. into the substrate, there arise someproblems of breakage of line between the wiring pattern and theconnection portion, the dislocation of chip, and the like.

[0030] It is another object of the present invention to provide a wiringpattern formation and transfer material for incorporating a fine wiringpattern or circuit components into a circuit substrate, morespecifically, a wiring pattern formation and transfer material capableof mounting a circuit component etc. on the circuit substrate accuratelyand at a low cost.

[0031] It is a further object of the present invention to provide awiring pattern on which a wiring pattern and circuit components areformed by the use of a wiring pattern formation and transfer material ora wiring pattern and circuit component formation and transfer material.

[0032] In order to achieve the above-mentioned object, a transfermaterial according to the first configuration of the present inventionincludes at least three layers of a first metal layer as a carrier, asecond metal layer as a wiring pattern, and a peel layer that issandwiched between the first metal layer and the second metal layer andallows the first metal layer and the second metal layer to be adheredreleasably, wherein a convex portion corresponding to the wiring patternis formed on the surface portion of the first metal layer, and the peellayer and the second metal layer are formed on a region of the convexportions.

[0033] A transfer material according to the second configuration of thepresent invention includes a transfer material including at least twolayers, a first metal layer as a carrier, and a second metal layer as awiring pattern, wherein a circuit component is formed on the first metallayer by a printing method for electrically connecting to the secondmetal layer.

[0034] Furthermore, in order to achieve the object, a first method forproducing a transfer material of the present invention includes forminga peel layer on a first metal layer, forming a second metal layer on thepeel layer, and etching the second metal layer, the peel layer and thesurface portion of the first metal layer by a chemical etching process,thereby forming the second metal layer and the peel layer into thewiring pattern, and at the same time, forming a convex and concaveportion having a convex portion corresponding to the wiring pattern onthe surface portion of the first metal layer.

[0035] With the transfer material of the second configuration, it ispossible to form circuit components such as an inductor, a capacitor,and a resistor, etc. by printing in one process. In particular, theformation of the resistor becomes easy. Moreover, the circuit componentsare not necessarily limited to these passive materials, and an activecomponent such as a semiconductor chip, etc. can be formed.

[0036] Furthermore, mounting of the circuit components by using a solderetc. becomes unnecessary, thus simplifying a mounting process.Furthermore, since the soldering connection is reduced, the reliabilityof the wiring substrate can be improved. Furthermore, since the circuitcomponents are formed on the transfer material by printing, as comparedwith the case where component chips are mounted by soldering, the heightof the circuit components can be reduced, thus facilitating the transferwhile embedding the components into the substrate and the integration ofthe components into the substrate. Furthermore, the circuit componentscan be placed freely, for example, it is possible to make the wiringdistance from the circuit components to the integrating capacitor, etc.the shortest, thereby improving the high frequency property.

[0037] Furthermore, in the transfer material of the secondconfiguration, after transfer, by forming new second metal layer orwiring pattern or component pattern on the first metal layer that is apeeled carrier, it is possible to reuse the first metal layer. And theconfiguration of the wiring pattern is not particularly limited.Therefore, low cost can be realized, and furthermore, it is useful fromthe viewpoint of industrial applicability.

[0038] Furthermore, a first method for producing a transfer material ofthe present invention includes forming a second metal layer into awiring pattern on the first metal layer, and forming a circuit componentby a printing method for electrically connecting to the second metallayer.

[0039] Furthermore, a second method for producing a transfer material ofthe present invention includes forming a peel layer and a second metallayer on a first metal layer, processing the second metal layer and thepeel layer into a wiring pattern, and forming a circuit component by aprinting method on the second metal layer for electrically connectingthe second metal layer.

[0040] The second metal layer that is a wiring pattern can be formeddirectly on the first metal layer that is a carrier by a plating method,an evaporation method, a sputtering method, or the like. At theformation of the second meat layer, similarly, a thin resistor film canbe formed by a sputtering method, and the like.

[0041] Furthermore, a third method for producing a transfer material ofthe present invention includes an electrically insulating substrate, anda wiring pattern formed on at least one principal plane of theelectrically insulating substrate by a transfer method by the use of thetransfer material according to the first configuration, wherein thewiring pattern is formed in the concave portion formed on the principalplane.

[0042] Furthermore, a wiring substrate according to the secondconfiguration of the present invention has an inner via hole structurein which a plurality of wiring substrates are laminated, wherein atleast one layer has a wiring substrate according to the firstconfiguration.

[0043] Furthermore, a wiring substrate according to the thirdconfiguration of the present invention includes an electricallyinsulating substrate, and a wiring pattern and a circuit component thatare formed on at least one principal plane of the electricallyinsulating substrate by a transfer method by the use of the transfermaterial according to the second configuration, wherein the circuitcomponent is electrically connected to the wiring pattern, and thecircuit component and the wiring pattern are embedded in the principalplane.

[0044] Furthermore, a wiring substrate according to the fourthconfiguration of the present invention has an inner via hole structurein which a plurality of wiring substrates are laminated, wherein atleast one layer has a wiring substrate according to the thirdconfiguration.

[0045] Furthermore, a first method for producing a wiring substrate ofthe present invention using the transfer material according to the firstconfiguration includes pressing the side of the transfer material wherethe wiring pattern metal layer including at least a second metal layeris formed onto at least one principal plane of an uncured base materialsheet, and peeling off a first metal layer adhered to the second metallayer from the second metal layer, thereby transferring the wiringpattern metal layer to the base material sheet.

[0046] Furthermore, a second method for producing a wiring substrate ofthe present invention includes providing a ceramic sheet with a throughhole, placing a constrained sheet, having an inorganic composition thatsubstantially is not sintered nor shrunk at the firing temperature ofthe ceramic sheet as a main component, on both surfaces of the ceramicsheet provided with a through hole, firing the ceramic sheet togetherwith the constrained sheet, after firing, removing the constrainedsheet, filling the through hole with a thermosetting conductivecomposition so as to form a ceramic substrate having a via conductor,pressing the side where the wiring pattern metal layer including atleast a second metal layer is formed of the transfer material accordingto the first configuration onto at least one principal plane of anuncured base material sheet including a thermosetting resin composition,peeling off the first metal layer adhered to the second metal layer viathe peel layer from the second metal layer, thereby transferring thewiring pattern metal layer to the base material sheet, providing a basematerial sheet including the thermosetting resin composition with athrough hole before or after the transfer, filling the through hole witha conductive composition so as to form a composite wiring substratehaving a via conductor, laminating the ceramic substrate and thecomposite wiring substrate, and heating and pressing the laminate so asto form a multi-layered wiring substrate.

[0047] Furthermore, a third method for producing a wiring substrate ofthe present invention using the transfer material according to thesecond configuration includes: pressing the side of the transfermaterial where the wiring pattern metal layer including at least asecond metal layer is formed onto at least one principal plane of anuncured base material sheet, and peeling off the first metal layer,thereby transferring at least the second metal layer and the circuitcomponent to the base material sheet.

[0048] Furthermore, a fourth method for producing a wiring substrate ofthe present invention includes providing a ceramic sheet with a throughhole, placing a constrained sheet, having an inorganic composition thatsubstantially is not sintered nor shrunk at the firing temperature ofthe ceramic sheet as a main component, on both surfaces of the ceramicsheet provided with a through hole, firing the ceramic sheet togetherwith the constrained sheet, after firing, removing the constrainedsheet, filling the through hole with a thermosetting conductivecomposition so as to form a ceramic substrate having a via conductor,pressing the side where the wiring pattern metal layer including atleast a second metal layer is formed of the transfer material accordingto the second configuration onto at least one principal plane of anuncured base material sheet including a thermosetting resin composition,peeling off the first metal layer adhered to the second metal layer viathe peel layer from the second metal layer, thereby transferring thewiring pattern metal layer to the base material sheet, providing a basematerial sheet including the thermosetting resin composition with athrough holes before or after the transfer, filling the through holewith a conductive composition so as to form a composite wiring substratehaving a via conductor, laminating the ceramic substrate and thecomposite wiring substrate, and heating and pressing the laminate so asto form a multi-layered wiring substrate.

[0049] With the transfer material of the second configuration, it ispossible to transfer the circuit components onto any of the layers ofthe multi-layered substrate, and further the components can be placedfreely. Therefore, the degree of freedom in designing the electriccircuit is radically improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0050]FIG. 1 is a cross-sectional view showing a schematic configurationof a wiring pattern formation and transfer material (hereinafter, atransfer material will be referred to) (a first transfer material)according to a first embodiment of the present invention.

[0051]FIG. 2 is a cross-sectional view showing a schematic configurationof a transfer material (a second transfer material) according to asecond embodiment of the present invention.

[0052]FIG. 3 is a cross-sectional view showing a schematic configurationof a transfer material (a third transfer material) according to a thirdembodiment of the present invention.

[0053]FIGS. 4A to 4F are cross-sectional views schematically showing aprocess for producing the first transfer material.

[0054]FIGS. 5A to 5E are cross-sectional views schematically showing aprocess for producing the second transfer material.

[0055]FIGS. 6A to 6E are cross-sectional views schematically showing aprocess for producing the third transfer material.

[0056]FIGS. 7A to 7C are cross-sectional views schematically showing aprocess for producing a composite wiring substrate using the transfermaterial of the present invention.

[0057]FIG. 8 is a cross-sectional view showing a schematic configurationof a ceramic wiring substrate produced by using the transfer material ofthe present invention.

[0058]FIG. 9 is a cross-sectional view showing a schematic configurationof the ceramic wiring substrate shown in FIG. 8 on which a semiconductorchip is flip-chip mounted.

[0059]FIGS. 10A to 10J are cross-sectional views schematically showingone example of a process for producing a multi-layered wiring substrateusing the transfer material of the present invention.

[0060]FIG. 11 is a cross-sectional view showing one example of aschematic configuration of the multi-layered wiring substrate producedby using the transfer material of the present invention.

[0061]FIG. 12 is a cross-sectional view showing another example of aschematic configuration of the multi-layered wiring substrate producedby using the transfer material of the present invention.

[0062]FIG. 13 is a cross-sectional view showing a further example of aschematic configuration of the multi-layered wiring substrate producedby using the transfer material of the present invention.

[0063]FIG. 14 is a cross-sectional view showing a still further exampleof a schematic configuration of the multi-layered wiring substrateproduced by using the transfer material of the present invention.

[0064]FIG. 15 is a cross-sectional view showing a further example of aschematic configuration of the multi-layered wiring substrate producedby using the transfer material of the present invention.

[0065]FIGS. 16A to 16C are cross-sectional views schematically showingone example of a process for producing a multi-layered wiring substrateusing the transfer material of the present invention.

[0066]FIGS. 17A to 17C are cross-sectional views schematically showinganother example of a process for producing a multi-layered wiringsubstrate using the transfer material of the present invention.

[0067]FIGS. 18A to 18E are cross-sectional views schematically showing afurther example of a process for producing a multi-layered wiringsubstrate using the transfer material of the present invention.

[0068]FIGS. 19A and 19B are cross-sectional views showing a schematicconfiguration of a circuit component and wiring pattern formation andtransfer material (a fourth transfer material) according to a fifthembodiment of the present invention.

[0069]FIG. 20 is a cross-sectional view showing a schematicconfiguration of a circuit component and wiring pattern formation andtransfer material (a fifth transfer material) according to a sixthembodiment of the present invention.

[0070]FIG. 21 is a cross-sectional view showing a schematicconfiguration of a circuit component and wiring pattern formation andtransfer material (a sixth transfer material) according to a seventhembodiment of the present invention.

[0071]FIGS. 22A to 22G′ are cross-sectional views schematically showinga process for producing a multi-layered circuit component using thefourth transfer material of the present invention.

[0072]FIGS. 23A to 23H are cross-sectional views schematically showing aprocess for producing a multi-layered circuit component using the fifthtransfer material of the present invention.

[0073]FIGS. 24A to 24H are cross-sectional views schematically showingan outline process for producing a multi-layered circuit component usingthe sixth transfer material of the present invention.

[0074]FIG. 25 is a cross-sectional view showing a multi-layered circuitsubstrate produced by using the fourth to sixth transfer materials.

[0075]FIGS. 26A to 26C are cross-sectional views schematically showing aprocess for producing a single layered wiring substrate that forms eachlayer of the multi-layered circuit substrate shown in FIG. 25 by usingthe sixth transfer material of the present invention; FIGS. 26A′ to 26C′are cross-sectional views showing each layer of the multi-layeredcircuit substrate produced by the process shown in FIGS. 26A to 26C; andFIG. 26D′ is a cross-sectional view showing a bottom layer wiringsubstrate of the multi-layered circuit substrate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0076] Hereinafter, the present invention will be described morespecifically with reference to embodiments.

[0077] First Embodiment

[0078] One example of a wiring pattern formation and transfer materialaccording to a first embodiment of the present invention (hereinafter, afirst transfer material will be referred to) is described. FIG. 1 is across-sectional view showing a schematic configuration of the firsttransfer material.

[0079] As shown in FIG. 1, the first transfer material includes a firstmetal layer 101 having a concave and convex portion (for example, theheight of the convex portion is about 1 to 12 μm) on a surface portionthereof. The convex portion of the first metal layer 101 corresponds toa wiring pattern. A peel layer 102 made of an organic layer or a metalplating layer and a second metal layer 103 are formed on the convexportions. Namely, the first transfer material has a three-layeredstructure in which the first metal layer 101 is adhered to the secondmetal layer 103 with the peel layer 102 sandwiched therebetween.

[0080] In the first transfer material, the second metal layer 103 is awiring-pattern and the first metal layer 101 serves as a carrier fortransferring the wiring pattern to a substrate. The first metal layer101 transfers the second metal layer 103 that is a wiring pattern to thesubstrate, and then the first metal layer 101 is peeled off from thesubstrate together with the peel layer 102.

[0081] For example, a method for producing the first transfer materialincludes the steps of:

[0082] (a) forming a three-layered structure by forming the second metallayer containing the same metal component as that contained in the firstmetal layer on the first metal layer with the peel layer made of anorganic layer or a metal plating layer sandwiched between the first andsecond metal layers; and

[0083] (b) processing not only the second metal layer and the peel layerbut also the surface portion of the first metal layer into the wiringpattern by a chemical etching process, thus to form a concave and convexportion on the surface portion of the first metal layer.

[0084] With this production method, it is possible to form the secondmetal layer into a fine wiring pattern by a chemical etching processsuch as photolithography, etc. Furthermore, since a metal foil formingthe wiring pattern (second metal layer) contains the same material asthat contained in the metal foil forming a carrier (first metal layer),it is possible to form the convex and concave portion having the samepattern as the wiring pattern of the second metal layer on the firstmetal layer that forms the carrier in one etching process.

[0085] Furthermore, in the first transfer material of this embodiment,the same transfer material can be reproduced by reusing the first metallayer peeled off after use, and by forming the second metal layer havingthe same shape as the convex portion of the first metal layer on thefirst metal layer with the peel layer such as a plating layer etc.sandwiched between the first and second metal layers. The first metallayer also can be reused for the other applications of use, for example,for a pattern formation material for a letterpress printing method.Therefore, since the first transfer material of this embodiment can makeeffective use of resources, it is advantageous from the viewpoint ofsaving resources and reducing waste. The same is true in the second andthird transfer materials described in the other embodiments.

[0086] Moreover, it is also possible to form circuit components such asan inductor, a capacitor, a resistor, a semiconductor device, or thelike, for electrically connecting to the wiring pattern of the transfermaterial of this embodiment, and to transfer them to the substratetogether with the wiring pattern. It is preferable that the passivecomponents such as inductor, capacitor, and resistor, etc. are formed onthe substrate by a printing method, for example a screen printingmethod.

[0087] Second Embodiment

[0088] One example of a transfer material according to a secondembodiment of the present invention (hereinafter, a second transfermaterial will be referred to) is described. FIG. 2 is a cross-sectionalview showing a schematic configuration of the second transfer material.

[0089] As shown in FIG. 2, the second transfer material includes a firstmetal layer 101 having a concave and convex portion on a surface portionthereof. The convex portion corresponds to a wiring pattern. The secondtransfer material has a four-layered structure in which a peel layer 102made of an organic layer or a metal plating layer and a second metallayer 103 are formed on the convex portion, and further a third metallayer 104 is formed on the second metal layer 103. The first metal layer101 is adhered to the second metal layer 103 with the peel layer 102sandwiched therebetween.

[0090] In the second transfer material, the second metal layer 103 andthe third metal layer 104 make a two-layered wiring pattern and thefirst metal layer 101 serves as a carrier for transferring the wiringpattern to the substrate. Therefore, the first metal layer 101 transfersthe second metal layer 103 and the third metal layer 104, which are thewiring patterns, to the substrate, and then is peeled off from thesubstrate together with the peel layer 102.

[0091] For example, a method for producing the second transfer materialincludes steps of:

[0092] (a) forming a three-layered structure by forming the second metallayer containing the same metal component as that contained in the firstmetal layer on the first metal layer with the peel layer made of anorganic layer or a metal plating layer sandwiched between the first andsecond metal layers;

[0093] (b) forming a plating resist on an arbitrary region on the secondmetal layer so as to make an exposed region that is not covered with theplating resist into a wiring pattern;

[0094] (c) forming the third metal layer made of a plating layer on theexposed region of the wiring pattern on the surface of the second metallayer by pattern plating;

[0095] (d) forming the third metal layer into the convex portion of thewiring pattern on the second metal layer by peeling off the platingresist; and

[0096] (e) selectively removing, by a chemical etching process, thesecond metal layer, the peel layer, and the upper part of the firstmetal layer of the region in which the third metal layer is not formed.

[0097] In this producing method, when the same metal component as thesecond metal layer is used for the third metal layer, for example, whena copper plating layer (third metal layer) is formed on the copper foil(second metal layer), it is possible to form the second and third metallayers into a fine wiring pattern for the reason as mentioned in thefirst embodiment and further because an additive method is employed.

[0098] Furthermore, since the second metal layer and the peel layer arethinner than the third metal layer, they can be removed in a short-timeetching. Basically, the third metal layer can be maintained with thethickness of the third metal layer hardly reduced. Therefore, thethickness of the wiring pattern can be controlled freely.

[0099] On the other hand, when a metal different from that of the secondmetal layer is used for the third metal layer, for example, when a gold(third metal layer) is formed on the copper foil (second metal layer) bypattern plating, the third metal layer serves as an etching resist.Therefore, it is possible to remove selectively the second metal layer,the peel layer, and the upper surface of the first metal layer on theregion in which the third metal layer having the wiring pattern is notformed. Furthermore, when gold is used for the third metal layer, thetop layer of the wiring pattern of the transfer material is gold.Therefore, when for example, a bare chip, a bare SAW (Surface AcousticWave) filter, or the like is flip-chip mounted on the wiring pattern, alow resistance and stable connection can be realized. Moreover, the sameeffect can be obtained when silver is used for the third metal layer.

[0100] Moreover, it is preferable in the production method that beforethe third metal layer is formed on the second metal layer, the surfaceof the second metal layer is roughened. The term “before the third metallayer is formed” means that before the plating resist as a mask forforming the wiring pattern is formed on the second metal layer, orbefore the third metal layer is formed along the wiring pattern on thesecond metal layer on which masking is performed in the wiring pattern.In this way, when the surface of the second metal layer is roughened,the adhesion between the second metal layer and the third metal layer isimproved.

[0101] It is preferable in the production method that the third metallayer is formed on the second metal layer by electrolytic plating. Whenthe third metal layer or the metal layer for forming a wiring pattern isformed by electrolytic plating, appropriate adhesion can be obtained onthe adhering surface between the second metal layer and the third metallayer. Furthermore, even if, for example, the etching process, etc. iscarried out, no gap occurs between the metal layers, so that anexcellent wiring pattern can be formed. On the other hand, the patternmay be formed by masking the wiring pattern after the third metal layeris formed on the second metal layer by panel plating. This case providesan effect of preventing the surface oxidization of the second metallayer after transfer and improving the soldering wettability.

[0102] It is preferable in the production method that the second andthird metal layers as well as the surface of the first metal layer areprocessed into the wiring pattern by a chemical etching process.

[0103] For the same reason as mentioned above, it is preferable in theproduction method that the second metal layer includes at least onemetal selected from the group consisting of copper, aluminum, silver andnickel, particularly, copper. It is desirable that the first metal layerincludes the same metal component as the second metal component becausethe convex portion having the same shape as that of the wiring pattern(second metal layer) is formed on the surface of the first metal layer,because a convex portion having the same shape as the wiring pattern(second metal layer) is formed on the surface of the first metal layerwhen the second metal layer is etched by a chemical etching process. Inparticular, the first and second metal layers are formed of a copperfoil, and more preferably, an electrolytic copper foil.

[0104] The method for producing the first and second metal layers is notparticularly limited. For example, the well-known method for producingmetal foil can be employed.

[0105] For a treatment for roughening the surface, for example, ablackening treatment, a soft etching treatment, a sandblast treatment,and the like, can be employed.

[0106] Moreover, it is also possible to form circuit components such asan inductor, a capacitor, a resistor, a semiconductor device, or thelike, for electrically connecting to the wiring pattern of the transfermaterial of this embodiment, and to transfer them to the substratetogether with the wiring pattern. It is preferable that the passivecomponents such as inductor, capacitor, and resistor, etc. are formed onthe substrate by a printing method, for example a screen printingmethod.

[0107] Third Embodiment

[0108] One example of a transfer material according to a thirdembodiment of the present invention (hereinafter, a third transfermaterial will be referred to) is described. FIG. 3 is a cross-sectionalview showing a schematic configuration of the third transfer material.

[0109] As shown in FIG. 3, the third transfer material includes a firstmetal layer 101 having a concave and convex portion on a surface portionthereof. The convex portion corresponds to a wiring pattern. The thirdtransfer material has a five-layered structure in which a peel layer 102made of an organic layer or a metal plating layer and a second metallayer 103 are formed on the convex portion, further a third metal layer104 is formed thereon, and further a fourth metal layer 105 is formedthereon. The first metal layer 101 is adhered to the second metal layer103 via the peel layer 102.

[0110] In the third transfer material, the second metal layer 103, thethird metal layer 104 and the fourth metal layer 105 make athree-layered wiring pattern. The first metal layer 101 serves as acarrier for transferring the wiring pattern to the substrate. The firstmetal layer 101 transfers the second metal layer 103, the third metallayer 104 and the fourth metal layer 105, which serve as the wiringpattern, to the substrate, and then is peeled off from the substratetogether with the peel layer 102.

[0111] For example, a method for producing the third transfer materialincludes the steps of:

[0112] (a) forming a three-layered structure by forming the second metallayer containing the same metal component as the first metal layer onthe first metal layer with a peel layer sandwiched between the first andsecond metal layers;

[0113] (b) forming a plating resist on an arbitrary region on the secondmetal layer so as to make an exposed region that is not covered with theplating resist into a wiring pattern;

[0114] (c) forming the third metal layer made of a plating layer on theexposed region of the wiring pattern on the surface of the second metallayer;

[0115] (d) on the third metal layer, forming a fourth metal layer of ametal component that is different from the components of the first tothird metal layers and that is chemically stable with respect to anetching liquid corroding the first to third metal layers;

[0116] (e) forming the third and fourth metal layers into a convexportion of the wiring pattern by peeling off the plating resist; and

[0117] (f) selectively removing the second metal layer, the peel layer,and the upper part of the first metal layer of the region in which thethird and fourth metal layers are not formed by a chemical etchingprocess.

[0118] With this production method, it is possible to form a fine wiringpattern for the reason as mentioned in the first embodiment and furtherbecause an additive method is employed. Furthermore, the thickness ofthe wiring pattern can be controlled freely.

[0119] It is preferable in the production method that before the thirdmetal layer is formed on the second metal layer, the surface of thesecond metal layer is roughened. The term “before the third metal layeris formed” means that before the plating resist for forming the wiringpattern is formed on the second metal layer, or before the third metallayer is formed along the wiring pattern on the second metal layer onwhich masking is performed in the wiring pattern. In this way, when thesurface of the second metal layer is roughened, the adhesion between thesecond metal layer and the third metal layer is improved.

[0120] It is preferable in the production method that the third metallayer is formed on the second metal layer by electrolytic plating. Whenthe third metal layer or the metal layer for forming the wiring patternis formed by electrolytic plating, appropriate adhesion can be obtainedon the adhering surface between the second metal layer and the thirdmetal layer. Furthermore, even if, for example, the etching process etc.is carried out, no gap occurs between the metal layers, so that anexcellent wiring pattern can be formed.

[0121] On the other hand, the pattern may be formed by masking on thewiring pattern after the third metal layer is formed on the second metallayer by panel plating. This case provides an effect of preventing thesurface oxidation of the second metal layer after transfer and improvingthe soldering wettability.

[0122] Furthermore, it is preferable in the production method that thefourth metal layer is formed on the third metal layer by electrolyticplating. It is preferable that as a material for the fourth metal layer,by selecting a component that is different from the components of thefirst to third metal layers, that is, a metal component chemicallystable with respect to an etching liquid corroding the first to thirdmetal layers, the second, third, and fourth metal layers can beprocessed into the wiring pattern together with the surface portion ofthe first metal layer without reducing the thickness even in thechemical etching process of the step (f).

[0123] For the same reason mentioned above, it is preferable in theproduction method that the second and third metal layers include atleast one metal selected from the group consisting of copper, aluminum,silver and nickel, particularly, copper. It is desirable that the firstmetal layer contains the same metal component as the component containedin the second metal component because a convex portion having the sameshape as the wiring pattern (second metal layer) is formed on thesurface of the first metal layer when the second metal layer is etchedby a chemical etching process. In particular, these metal layers areformed of a copper foil, more preferably, an electrolytic copper foil.On the other hand, a preferable example of the fourth metal layerincludes, for example, a plating layer of Ag, Au, or the like, havingchemical stability and the low resistance property.

[0124] The method for producing the first and second metal layers is notparticularly limited. For example, the well-known method for producing ametal foil can be employed.

[0125] For a treatment for roughening the surface, for example, ablackening treatment, a soft etching treatment, a sandblast treatment,and the like can be employed.

[0126] Moreover, it is preferable in the above-mentioned first, second,and third transfer materials of the first to third embodiments that theadhesive strength between the first metal layer and the second metallayer via the peel layer is weak, for example, 50 N/m (gf/cm) or less.As the peel layer, an organic layer having adhesive strength and athickness of much thinner than 1 μm can be used. An example of the peellayer includes an urethane resin, an epoxy resin, a phenol resin, andthe like. However, the peel layer is not necessarily limited thereto,and other resin such as a thermoplastic resin can be used. However, thepeel layer having a thickness of 1 μm or more deteriorates the peelingproperty, which may make the transfer difficult.

[0127] Furthermore, in order to lower the adhesiveness in the first tothird transfer materials intentionally, a plating layer may beinterposed as the peel layer. A metal plating layer having a thicknessof much thinner than 1 μm, for example, a nickel plating layer, anickel-phosphorous alloy layer, an aluminum plating layer, a chromeplating layer, or the like, can be interposed between the copper foils(first and second metal layers) so as to provide a peeling property.This facilitates peeling off the second metal layer from the first metallayer after the second metal layer is transferred to the substrate, thustransferring only the second metal layer to the substrate. A suitablethickness of the peel layer formed of the metal layer is about 100 nm to1 μm. Since the cost of the process is increased with the increase inthickness, the thickness is desirably less than 1 μm.

[0128] Furthermore, in the first to third transfer materials, if thepeel layer intentionally is formed by Au plating so that it can bepeeled off from the first metal layer easily, when the first metal layeris peeled off from the substrate after transfer the peel layer remainson the surface of the second metal layer of the wiring pattern. Thus, awiring pattern whose surface is Au plating treated can be obtained. Thewiring pattern exhibits an excellent FC mounting (flip-chip mounting)property, components mounting property, and the like.

[0129] Furthermore, it is preferable in the first to third transfermaterials that the first metal layer includes at least one metalselected from the group consisting of copper, aluminum, silver andnickel, and particularly preferably copper. It is preferable that thesecond metal layer, as in the first metal layer, includes at least onemetal selected from the group consisting of copper, aluminum, silver andnickel, and particularly preferably, copper. Moreover, the metals may beone kind, or may be two kinds or more.

[0130] Furthermore, it is preferable in the first to third transfermaterials that the first metal layer includes the same metal componentas the second metal because two-layered structure of metal layers areprocessed at the same time when, for example, an etching process iscarried out. In this case, since there is no difference in thecoefficient of thermal expansion between the first metal layer and thesecond metal layer, the pattern distortion is not likely to occur whenheating. Therefore, it is suitable for the transfer of the fine wiringpattern. When the plating layer is used for the peel layer, desirably, acopper etching liquid can be used for processing. However, the kinds ofmetal are not particularly limited as long as the first and the secondmeals include the same materials. However, preferably they are formed ofa copper foil, and more preferably an electrolytic copper foil becauseof its excellent conductivity. Moreover, the metals may be one kind, ormay be two kinds or more.

[0131] Furthermore, in the first to third transfer materials, theaverage roughness (Ra) of the center line of the surface of the secondmetal layer is 2 μm or more, and more preferably 3 μm or more. In thefirst transfer material, when the average roughness (Ra) of the centerline of the surface is less than 2 μm, the adhesion with respect to thesubstrate to be transferred may be insufficient. On the other hand, inthe second and third transfer materials, when the average roughness (Ra)of the center line of the surface is less than 2 μm, the adhesionbetween the metal layers forming the multi-layered wiring pattern maybecome insufficient, and the etching liquid may enter the gap betweenthe metal layers so as to make the wiring pattern deficient.

[0132] Furthermore, in the first to third transfer materials, thethickness of the second metal layer is preferably 1 to 18 μm, and morepreferably 3 to 12 μm. When the thickness is less than 3 μm, when thesecond metal layer is transferred to the substrate, an excellentelectric conductivity may not be exhibited. On the contrary, when thethickness is 18 μm or more, it may be difficult to form a fine wiringpattern.

[0133] Furthermore, in the first to third transfer materials, thethickness of the first metal layer is preferably 4 to 40 μm, and morepreferably 20 to 40 μm. The first metal layer serves as a carrier, andat the same time has a structure in which the surface layer portion isetched like the wiring layer so as to have a convex and concave portion.Therefore, the first metal layer is desired to have a sufficientthickness. Furthermore, since the first to third transfer materials havea carrier made of a metal layer (first metal layer), they exhibit thesufficient mechanical strength or thermal resistance with respect to thethermal distortion or stress distortion in the direction of the plane,which are generated at the time of transfer.

[0134] The total thickness of the first to third transfer materials ispreferably 40 to 150 μm, and more preferably 40 to 80 μm. Furthermore,the line width of the wiring pattern generally is required to be aboutup to 25 μm, as a fine line width. Also in the present invention, such aline width is preferable.

[0135] Moreover, it is also possible to form circuit components such asan inductor, a capacitor, a resistor, a semiconductor device, or thelike, for electrically connecting to the wiring pattern of the transfermaterial of this embodiment and to transfer them to the substratetogether with the wiring pattern. It is preferable that the passivecomponents such as inductor, capacitor, and resistor, etc. are formed onthe substrate by a printing method, for example a screen printingmethod.

[0136] Fourth Embodiment

[0137] In this embodiment, a method for producing the wiring substrateusing the various kinds of wiring pattern formation and transfermaterials of the present invention (first to third transfer materials),and a wiring substrate produced by the production method will bedescribed.

[0138] The following are two methods for producing the wiring substrateusing the transfer materials according to the present invention.

[0139] A first method includes the following steps:

[0140] (h) preparing at least one of the first to third transfermaterials described in the first to third embodiments and placing thematerial(s) so that the wiring layer side (side on which the secondmetal layer etc. is formed) of the material is in contact with at leastone surface of a base material sheet (a material for the substrate) soas to adhere thereto, and

[0141] (i) transferring only the wiring layer to the base material sheetby peeling off the first metal layer from the transfer material.

[0142] Thus, it is possible to produce a wiring substrate on which finewiring patterns are formed in the concave portion on the base materialsheet. Furthermore, since the wiring portion of this wiring substratehas a concave shape, this concave portion can be used for positioning.This configuration is excellent in, for example, the flip chip mountingetc. of a semiconductor.

[0143] Furthermore, the second production method is a method forproducing a multi-layered substrate and includes a step for laminatingtwo or more of the wiring substrates produced by the first productionmethod. The first production method enables the transfer formation ofthe wiring pattern at a low temperature of 100° C. or less. Therefore,in any cases where a ceramic green sheet is used or where athermosetting resin sheet is used for the base material sheet, it ispossible to keep the sheet uncured even after the wiring pattern istransferred. This allows a thermal curing and shrinking of the uncuredwiring substrates together at a time after the uncured wiring substratesare laminated. Therefore, unlike a conventional method for producing amulti-layered substrate repeating the process in which the wiringsubstrate is laminated and subjected to a curing and shrinking treatmentone by one, the method for producing this embodiment has an advantage inthat it is not necessary to correct the curing and shrinking with eachlayer. Therefore, the steps can be simplified.

[0144] This method allows the formation of a multi-layered wiringsubstrate having fine wiring patterns. However, in the multi-layeredwiring substrate, the wiring patterns formed on the wiring substrate ofthe inside layer are not required to have a concave shape. Therefore,with a transfer material for forming this wiring pattern, the surfaceportion of the first metal layer is not necessarily formed in a concaveand convex shape and may be flat. In this case, for example, bycontrolling the time of the chemical etching process in the formation ofthe wiring pattern, it is possible to stop the process at the stage inwhich the peel layer is etched so as not to etch the first metal layer.Furthermore, when the peel layer is made of a plating layer containingNi, by using a base solution obtained by adding ammonium into copperchloride as an etching liquid, it is possible to remove only the copperfoil (wiring pattern) by an etching process and to remain the peellayer. This transfer material does not have a problem in the transferbecause a carrier copper foil (first metal layer) is peeled off afterbeing pressed onto the substrate, and the plating layer that is a peellayer also is peeled off together.

[0145] Furthermore, when the first transfer material is used, bypressing the first transfer material onto the base material sheet (amaterial for the substrate), the convex portions of the second metallayer and the first metal layer are embedded in the base material sheet.Thereafter, the first metal layer is peeled off, and then the wiringsubstrate has a concave portion on the surface and the wiring layer madeof the second metal layer at the bottom of the concave portion.

[0146] Furthermore, when the second transfer material is used bypressing the second transfer material onto the base material sheet, forexample, after the entire part of the second and third metal layers andthe convex portion of the first metal layer are embedded in the basematerial sheet, the first metal layer is removed. This allows theproduction of the two-layered wiring substrate having a concave portionof a depth that is substantially the same as a thickness of the convexportion of the first metal layer, and the second and third metal layersformed on the bottom of the concave portion.

[0147] Similarly, when the third transfer material is used, for example,after the entire part of the second, third and fourth metal layers andthe convex portion of the first metal layer are embedded in the basematerial sheet, the first metal layer is removed. This allows theproduction of the three-layered wiring substrate having a concaveportion of the depth that is substantially the same as the thickness ofthe convex portion of the first metal layer, and the second, third andfourth metal layers formed on the bottom of the concave portion.

[0148] It is preferable in the method for producing the first and thesecond wiring substrates that the base material sheet includes aninorganic filler and the thermosetting resin composition and has atleast one through hole which is filled with a conductive paste. Thismakes it easy to produce a composite wiring substrate for high-densitymounting having an excellent thermal conductivity and having an IVHstructure in which, for example, wiring patterns of the both sides ofthe substrate are electrically connected via the conductive paste.Furthermore, with the use of this base material sheet, in the formationof the wiring substrate, high temperature is not required, but treatingmay be carried out at a low temperature of, for example, about 200° C.,i.e. the curing temperature of the thermosetting resin.

[0149] The base material sheet preferably contains 70 to 95 weight % ofan inorganic filler and 5 to 30 weight % of a thermosetting resin, andmore preferably contains 85 to 90 weight % of an inorganic filler and 10to 15 weight % of a thermosetting resin. Since the base material sheetcontains inorganic fillers with a high concentration, by changing thecontent of inorganic fillers, the coefficient of thermal expansion,thermal conductivity, dielectric constant, and the like, can be setarbitrarily.

[0150] It is preferable that the inorganic filler includes at least oneinorganic filler selected from the group consisting of Al₂O₃, MgO, BN,AlN and SiO₂. By determining the kinds of inorganic fillerappropriately, it is possible to set, for example, the coefficient ofthermal expansion, thermal conductivity, and dielectric constant to thedesirable conditions. For example, it is possible to set the coefficientof thermal expansion of the base material sheet in the plane directionto the same level of the coefficient of thermal expansion of asemiconductor to be mounted, and to provide a high thermal conductivity.

[0151] The base material sheet using, for example, Al₂O₃, BN, AlN andthe like, among the inorganic fillers, is excellent in thermalconductivity. The base material sheet using MgO is excellent in thermalconductivity and capable of raising the coefficient of thermalexpansion. Furthermore, when SiO₂, particularly amorphous SiO₂, is used,a base material sheet having a small constant thermal expansion, a lightweight and low dielectric constant can be obtained. Moreover, theinorganic filler can be used singly or by combination of two kinds ormore of the inorganic fillers.

[0152] The base material sheet including the inorganic filler and thethermosetting resin composition can be produced by, for example, thefollowing method. First, a solvent for adjusting the viscosity is addedinto a mixture including the inorganic filler and the thermosettingresin composition so as to prepare a slurry having a desired slurryviscosity. An example of the solvent for adjusting the viscosityincludes, for example, methyl ethyl ketone, toluene, and the like.

[0153] Then, the slurry is formed into a film on a preliminarilyprepared mold release film by a doctor blade method, etc. and the filmis treated at a temperature below the curing temperature of thethermosetting resin so as to volatilize the solvent for adjusting theviscosity. Thereafter, the mold release film is removed so as to producea base material sheet.

[0154] The thickness of the film at the formation is appropriatelydetermined by the amount of the solvent for adjusting viscosity to beadded. Usually the thickness ranges from 80 to 200 μm. Furthermore, theconditions for volatilizing the solvent for adjusting viscosity areappropriately determined in accordance with the kinds of solvents foradjusting viscosity, kinds of thermosetting resins, or the like.However, usually, the volatilization is carried out at a temperature of70 to 150° C. for 5 to 15 minutes.

[0155] As the mold release film, usually, an organic film can be used.For example, it is preferable to use an organic film containing at leastone resin selected from the group consisting of, for example,polyethylene, polyethylene terephthalate, polyethylene naphthalate,polyphenylene sulfide (PPS), polyphenylene terephthalate, polyimide andpolyamide, and more preferably PPS.

[0156] Furthermore, another example of the base material sheet includesa reinforcer sheet impregnated with a thermosetting resin composition,and having at least one through hole filled with a conductive paste.

[0157] The reinforcer sheet is not particularly limited as long as it isa porous material capable of holding the thermosetting resin. However,it is preferable that the reinforcer sheet is at least one selected fromthe group consisting of a glass fiber woven fabric, a glass fibernon-woven fabric, a woven fabric of a thermal resistant organic fiberand a non-woven fabric of a thermal resistant organic fiber. An exampleof the thermal resistant organic fiber includes, for example, allaromatic polyamide (aramide resin), all aromatic polyester, polybutyleneoxide, and the like. In particular, aramide resin is preferable. Anotherexample of the base material sheet includes a film of polyimide etc. Byusing the film of polyimide etc., an excellent substrate having a finepattern of wiring and via conductor can be obtained.

[0158] The thermosetting resin is not particularly limited. However, itis preferable that a resin contains at least one selected from the groupconsisting of an epoxy resin, a phenol resin, a cyanate resin and apolyphenylene phthalate resin because of its excellent thermalconductivity. Furthermore, the thermosetting resin can be used singly orby combination of two kinds or more of the thermosetting resins.

[0159] Such a base material sheet can be produced, for example, byimmersing the reinforcer sheet into the thermosetting resin composition,and then drying to a half-cured state. It is preferable that theimmersion is carried out so that the rate of the thermosetting resinwith respect to the base material sheet is 30 to 60 weight %.

[0160] In the method for producing the multi-layered wiring substrate,it is preferable that when the base material sheet containing athermosetting resin is used, the wiring substrates are laminated by aheating and pressing treatment so as to cure the thermosetting resin.This can be performed sufficiently at a low temperature such as 200° C.,i.e., the curing temperature of the thermosetting resin.

[0161] Furthermore, another base material sheet includes a green sheetcontaining an organic binder, plasticizer, and ceramic powder, having atleast one through hole filled with a conductive paste. This basematerial sheet exhibits an excellent thermal resistance and thermalconductivity.

[0162] The ceramic powder preferably contains at least one ceramicselected from the group consisting of Al₂O₃, MgO, ZrO₂, TiO₂, BeO, BN,SiO₂, CaO and glass. More preferably, the ceramic powder is a mixture of50 to 55 weight % of Al₂O₃ and 45 to 50 weight % of glass power.Moreover, the ceramic can be used singly or in combination of two kindsor more of them.

[0163] An example of the binders to be used includes, for example,polyvinyl butyrate (PVB), acrylic resin, methyl cellulose resin, and thelike. An example of the plasticizer includes, for example, butyl benzylphthalate (BBP), dibutylphthalate (DBP), and the like.

[0164] Such a green sheet containing the ceramic powder can be producedby, for example, the same method as the method for producing the basematerial sheet including the inorganic filler and the thermosettingresin. Moreover, the treating conditions are appropriately determined bythe kinds of the component materials, etc.

[0165] It is preferable in the method for producing the multi-layeredwiring pattern that when the green sheet is used for the base materialsheet, the wiring substrates are laminated by heating and pressing thebase materials to be adhered and by sintering the ceramic powder byfiring.

[0166] The thickness of the base material sheet is usually 30 to 250 μm.

[0167] It is preferable that the base material sheet has at least onethrough hole and the through hole is filled with a conductive paste. Theposition of the through hole is not particularly limited as long as thethrough hole is formed so that it is in contact with the wiring pattern.However, it is preferable that through holes are positioned by equalintervals of 250 to 500 μm pitch.

[0168] The size of the through hole is not particularly limited.However, the diameter of the through hole is 100 to 200 μm, andpreferably 100 to 150 μm.

[0169] The method for forming through holes is appropriately determinedin accordance with the kinds of the base material sheet, etc. However,the preferable example of the method includes, for example, a carbondioxide gas laser process, a process with a punching machine, a bulkprocess with a mold, etc.

[0170] The conductive paste is not particularly limited as long it hasconductivity. However, usually, a resin containing a particulateconductive metal, and the like, can be used. An example of theconductive metal material to be used includes, for example, copper,silver, gold, silver-palladium, and the like. An example of thethermosetting resin includes, for example, an epoxy resin, a phenolresin, an acrylic resin, and the like. The amount of the conductivemetal material in the conductive paste is usually 80 to 95 weight %.Furthermore, when the base material sheet is a green sheet, glass and anacrylic binder are used instead of thermosetting resin.

[0171] Next, the method for adhering the transfer material to the basematerial sheet in the step (h) and the method for peeling off the firstmetal layer from the second metal layer in the step (i) are notparticularly limited. However, when the base material sheet includes athermosetting resin, for example, the adhering method and the peelingmethod can be carried out as follows.

[0172] First, the transfer material and the base material sheet areplaced as mentioned above, and heated and pressed so as to fuse andsoften the thermosetting resin in the base material sheet, thus allowingthe metal layer (the second metal layer, etc.) that forms the wiringpattern to be embedded in the base material sheet. Then, it is treatedat a softening temperature or a curing temperature of the thermosettingresin. In the latter case, the resin is cured. This allows the transfermaterial and the base material sheet to be adhered and the adhesionbetween the second metal layer and the base material sheet to be fixed.

[0173] The conditions for heating and pressing treatment is notparticularly limited as long as the thermosetting resin is not perfectlycured. However, the heating and pressing usually can be carried outunder the pressure of 9.8×10⁵ to 9.8×10⁶ Pa (10 to 100 kgf/cm²), at thetemperature of 70 to 260° C. for 30 to 120 minutes.

[0174] Then, after the transfer material and the sheet substrate areadhered to each other, for example, the first metal layer that is thecarrier layer is pulled so as to peel it off in the peel layer. Thereby,the first metal layer can be peeled off from the second metal layer.Namely, since the adhesive strength between the first metal layer andthe second metal layer via the peel layer is weaker than the adhesivestrength between the base material sheet and the second metal layer thatis a wiring layer, the adhering surface between the first metal layerand the second metal layer is peeled off, and only the second metallayer is transferred to the base material sheet while the first metallayer is peeled off. Curing of the thermosetting resin may be carriedout after the first metal layer is peeled off from the second metallayer.

[0175] When the base material sheet is the green sheet including aceramic, for example, the adhering method and peeling method can becarried out as follows. The transfer material and the base materialsheet are heated and pressed as mentioned above so as to allow the metallayer for forming the wiring pattern to be embedded into the basematerial sheet, thus adhering the base material sheet to the transfermaterial. Thereafter, similar to the above, forming materials of thetransfer material except the wiring layer (second metal layer, etc.) areremoved by peeling. Then, a constraint sheet is placed and laminated onone or both surfaces of the green sheet onto which the second metallayer forming the wiring pattern is transferred. The constraint sheetincludes an inorganic composition that substantially is not sintered norshrunk at the firing temperature of the green sheet. Thereafter, thebinder removing process and firing are carried out. Furthermore,thereafter the constraint sheet is removed, and thus a ceramic substrateincluding the wiring pattern formed of the second metal layer etc. canbe formed.

[0176] The conditions for heating and pressing when the transfer iscarried out are appropriately determined in accordance with the kinds ofthe thermosetting resin contained in the green sheet and conductivepaste. However, usually, the heating and pressing treatment is carriedout under the pressure of 9.8×10⁵ to 1.96×10⁷ Pa (10 to 200 kgf/cm²), ata temperature of 70 to 100° C. for 2 to 30 minutes. Therefore, thewiring pattern can be formed without damaging the green sheet.

[0177] The heating and pressing conditions for placing and laminatingthe constraint sheet including an inorganic composition thatsubstantially is not sintered nor shrunk at the firing temperature ofthe green sheet is appropriately determined in accordance with the kindsof the thermosetting resin contained in the green sheet and theconstraint sheet. However, usually, the conditions include a pressure of1.96×10⁶ to 1.96×10⁷ Pa (20 to 200 kgf/cm²), at a temperature of 70 to100° C. for 1 to 10 minutes.

[0178] The conditions for the treatment for removing the binder areappropriately determined in accordance with the kinds of binders, metalthat forms the wiring pattern, or the like. However, usually, thetreatment is carried out by the use of the electric furnace at atemperature of 500 to 700° C., with temperature rising time of 10 hours,and maintaining time of 2 to 5 hours. In particular, in the case of thecopper foil wiring pattern, a green sheet formed of an organic bindersuch as methacrylic methacrylic that is excellent in thermal deformationproperty is used, and the binder removing process and firing are carriedout in an atmosphere of nitrogen, that is, an atmosphere ofnon-oxidation.

[0179] The conditions for firing are appropriately determined inaccordance with the kinds of the ceramic and the like. However, usually,the firing is carried out in a belt furnace, at a temperature of 860 to950° C. for 30 to 60 minutes in the air or an atmosphere of nitrogen.

[0180] Herein, the second production method is described. When themultilayered substrate is produced in this method, each single layerwiring substrate that is produced by the above-mentioned method islaminated and the interlayer portion is adhered. Moreover, after aplurality of single layer substrates are laminated, the whole portioncan be adhered and fixed.

[0181] For example, when a multi-layered wiring substrate produced bythe use of a base material sheets including a thermosetting resin arelaminated, first, similar to the above, only the wiring layer (secondmetal layer etc.) is transferred to the base material sheet from thetransfer material so as to form a single layered wiring substrate by aheating and pressing treatment. When this wiring substrate is formed,the thermosetting resin is not subjected to the curing treatment andkept uncured. The plurality of single layer substrates are prepared andlaminated. Then, this laminate is heated and pressed at a curingtemperature of the thermosetting resin so as to cure the thermosettingresin, thereby adhering and fixing the place between the wiringsubstrates. When the heating and pressing temperature for transferringthe wiring layer in the single layer wiring substrate is set to be 100°C. or less, intentionally, even after the transfer, the base materialsheet can be used as a prepreg. Thus, it is possible to produce amulti-layered wiring substrate by adhering and fixing the laminate afterthe single layer wiring substrates are laminated instead of sequentiallylaminating the single layer wiring substrates.

[0182] With the use of the transfer material of the present invention, abuildup substrate having a glass-epoxy substrate etc. as a core layercan be produced by a method in which a wiring pattern is transferred toan uncured base material sheet to form it into single layered wiringsubstrates, and these single layered wiring substrates are sequentiallylaminated as in an uncured state, and the laminated substrates are curedas a whole.

[0183] Furthermore, for example, when a multi-layered substrate isproduced by laminating ceramic wiring substrates using a base materialsheet including a ceramic, as mentioned above, after the transfermaterial is pressed onto the base material sheet so as to transfer onlythe wiring layer (second metal layer etc), a plurality of the singlelayered ceramic wiring substrates are laminated and heating and pressingtreatment and firing of the ceramic are carried out. Thus, the placebetween the wiring substrates are adhered and fixed.

[0184] The number of the laminated layers in the multi-layered wiringsubstrates is not particularly limited. However, the number is usually 4to 10 layers, and as many as 20 layers is also possible. Furthermore,the total thickness of the multi-layered wiring substrate is usually 200to 1000 μm.

[0185] The wiring substrate forming the outermost layer of themulti-layered wiring substrate is excellent in electric connection.Therefore, as mentioned above, the wiring substrate forming theoutermost layer preferably has a structure in which a wiring layer(second metal layer etc.) is embedded in the concave portion of thesurface thereof by the use of the transfer material of the presentinvention (first, second or third transfer material). Furthermore,middle layer(s) other than the outermost layer of the multi-layeredwiring substrate may be a flat structure or may have a wiring layer(second metal layer, etc.) formed on the concave portion of the surface.

[0186] Hereinafter, a configuration of the wiring substrate of thepresent invention will be described in detail.

[0187]FIG. 8 shows a wiring substrate of a first embodiment produced byusing the transfer material of the present invention (first, second, orthird transfer material). The wiring substrate of the first embodimentincludes a wiring pattern 801 formed on a base material sheet 805. Atleast one surface of the base material sheet 805 is provided with atleast one concave portion on the bottom of which the wiring pattern 801is formed. Furthermore, on the wiring pattern 801, a plating layer 802of gold etc. is formed by a plating treatment.

[0188] According to this configuration, when a semiconductor isflip-chip mounted on the wiring substrate, as shown in FIG. 9, theconcave portion can be used for the positioning of a bump 904 formed ona semiconductor 905. Since a connection portion 903 between thesemiconductor 905 and the substrate is formed on the chemically stablegold plating etc., the contacting resistance becomes smaller and thereliability can be improved. Furthermore, since the plating treatment iscarried out by the use of the concave portion, it is possible to securea creeping distance, thus maintaining the reliability of the fine wiringpattern without occurrence of the short circuit etc.

[0189] It is preferable in the wiring substrate that the thickness ofthe wiring pattern layer/patterns is 3 to 35 μm. When the thickness isless than 3 μm, excellent conductivity may not be obtained. On the otherhand, when the thickness is more than 35 μm, it may be difficult to forma fine wiring pattern.

[0190] It is preferable in the wiring substrate that the depth of theconcave portion is 1 to 12 μm. When the depth is more than 12 μm, forexample, when a semiconductor is mounted, some bumps may not be broughtinto contact with the wiring pattern or it may take a long time to sealwith a sealing resin. On the other hand, when the depth is less than 1μm, the concave portion may not serve for the positioning of the bumps.

[0191] The second embodiment of the wiring substrate formed by thetransfer material of the present invention is a multi-layered wiringsubstrate in which, as shown in FIG. 10J, a wiring pattern (1002 etc.)is formed on the base material sheet 1001, at least one surface of thesubstrate has at least one concave portion and the wiring pattern isformed on the bottom portion of the concave portion. In thismulti-layered wiring substrate, by using the transfer material of thepresent invention, the wiring pattern can be formed on the base materialsheet that is an uncured base material sheet or a green sheet. Thus,after the single layered substrate is laminated, an entire laminate isadhered and fixed, and a base material sheet and metal foil wiringpatterns can be cured simultaneously. As a result, a multi-layeredwiring substrate including an interlayer via of each layer having a highposition accuracy can be obtained.

[0192] The third embodiment of the wiring substrate formed by thetransfer material of the present invention is a multi-layered wiringsubstrate having a laminate structure, as shown in FIG. 11. The laminatestructure includes an electrically insulating substrate 1608 formed of aceramic, and an electrically insulating substrate 1602 including atleast a thermosetting resin composition. The electrically insulatingsubstrate 1608 formed of a ceramic is formed in a state in which awiring pattern is prevented from projecting from the surface by usingthe transfer material of the present invention. Furthermore, it ispossible to laminate the electrically insulating sheet containing anuncured thermosetting resin and electrically insulating substrate formedof a ceramic and to cure them at relatively small pressure in one time.Thus, it is possible to attain the multi-layered substrate withoutdamaging the ceramic layer.

[0193] On the other hand, the multi-layered wiring substrate can beproduced by adhering it to an electrically insulating sheet containing athermosetting resin after the wiring pattern has been formed beforehandon the ceramic substrate by a printing method or firing. However, sincethe wiring pattern produced by a printing method becomes a projection,in the process of adhering the wiring pattern to the electric insulatingsheet containing a thermosetting resin composition, stress concentrationoccurs, from which cracks are generated in the ceramic substrate layer.

[0194] The fourth embodiment of the wiring substrate produced by usingthe transfer material of the present invention is a multi-layered wiringsubstrate including an electrically insulating substrate 1608 formed ofa ceramic, and an electrically insulating substrate 1602 including atleast a thermosetting resin composition, similar to the wiring substrateof the third embodiment, as shown in FIG. 12. Furthermore, an interlayervia hole 1603 filled with a conductive via composition is provided inthe predetermined position of each layer of the laminated electricinsulating substrates, and a wring pattern 1610 electrically connectedto the via holes 1608 is formed. Although this structure is a laminateof the ceramic substrate and a resin substrate, a multi-layered wiringconnection can be used that is the same as in the wiring rule of themulti-layered wiring substrate formed of only ceramic substrates or amulti-layered wiring substrate formed of only resin substrates.

[0195] In this case, as the conductive resin composition used for theinterlayer connection via of the ceramic substrates, a sintered bodyformed of metal powder and glass powder is used. On the other hand, asthe conductive resin composition used of the inter connection via of theresin substrate, a resin composition made of a mixture of metal powderand the thermosetting resin is used.

[0196] Furthermore, in the interface between the electrically insulatingsubstrate containing a thermosetting resin composition and the ceramicsubstrate, the wiring pattern layer formed on the ceramic substrate isnot projected from the surface and is incorporated in the ceramicsubstrate.

[0197] Furthermore, it is preferable in the firing process of theceramic substrate that the firing treatment is carried out after theconstraint sheet including an inorganic composition that substantiallyis not sintered nor shrunk at the firing temperature of the green sheetis placed on both surfaces or one surface of the green sheet on which awiring pattern is transferred. Thus, since the non-shrinkage sinteringin the plane direction can be realized, when laminating to the resinbase substrate, the common interlayer via positional data can beemployed.

[0198] Needless to say, after the wiring pattern may be formed on theceramic green sheet filled with the via paste by a printing method andby sintering, this is adhered to the electrically insulating sheetcontaining a thermosetting resin composition so as to form a interlayerconnection. However, since the wiring pattern by a printing methodbecomes a projection, in a process of adhering the electricallyinsulating sheet containing the thermosetting resin composition to theceramic green sheet, stress concentration occurs, from which cracks aregenerated in the ceramic substrate layer.

[0199] Furthermore, as shown in FIG. 13, by using the transfer materialof the present invention, it is possible to produce a multi-layeredwiring substrate in which a low resistance wiring is formed. The lowresistance wiring is produced by laminating a ceramic substrate 1708formed of an alumina substrate having a relatively high mechanicalstrength, and an aluminum nitride substrate having a high thermalconductivity, or the like, onto an electrically insulating substrate1702 containing at least a thermosetting resin composition. Herein, bothan interlayer via conductor used for the ceramic substrate and aninterlayer via conductor used for the resin based substrate are formedof the same thermosetting resin composition.

[0200] Needless to say, as the ceramic substrate used herein, a lowtemperature sintering ceramic capable of being sintered together withcopper, silver, etc, for example, alumina glass ceramic, Bi—Ca—Nb—Obased ceramic, and the like, may be used.

[0201] The fifth embodiment of the wiring substrate formed by the use ofthe transfer material of the present invention is a dissimilar laminatewiring substrate. As shown in FIG. 14, similar to the wiring substrateof the third or fourth embodiment, the dissimilar laminate wiringsubstrate has a laminate structure including an electric insulatingsubstrate containing a thermosetting resin composition and anelectrically insulating substrate containing a ceramic. In thisembodiment, electrically insulating substrates 1801 and 1802 formed ofdifferent kinds of ceramics each having a different composition arelaminated via the electrically insulating substrate 1807 including athermosetting resin.

[0202] According to this structure, it is possible to obtain adissimilar laminate between a magnetic ceramic and a dielectric ceramicor a dissimilar laminate between a dielectric ceramic having a highdielectric constant and a dielectric ceramic having a low dielectricconstant, which conventionally has been technically difficult to achievebecause of the difference in the firing temperatures or shrinkage rate,or mutual diffusion etc. at the time of sintering. Furthermore, in themethod for producing the dissimilar laminate wiring pattern substrate ofthe present invention, each wiring substrate is produced by transferringa wiring pattern such as a copper foil etc. to the green sheet oruncured thermosetting resin impregnated sheet. Thus, a laminate having alow resistant wiring in all layers can be obtained without being damagedat the time of laminate.

[0203] According to the wiring substrate according to the fifthembodiment, by interposing the electric insulating substrate including athermosetting resin composition between the ceramic substrates, it ispossible to laminate ceramic substrates, each having a differentsintering temperature. Thus, it is possible to produce easily, forexample, a dissimilar laminate wiring substrate in which each layer hasdifferent dielectric constant or a dissimilar laminate wiring substratein which a magnetic layer and dielectric layer are laminated.

[0204] Needless to say, after a wiring pattern is formed on a ceramicgreen sheet filled with via paste by a printing method and by firing,then the electrically insulating sheet containing a thermosetting resincomposition may be laminated onto the ceramic green sheet. However,since the wiring pattern by a printing method becomes a projection, inthe process of adhering the wiring pattern to electrically insulatingsheet containing a thermosetting resin composition, stress concentrationoccurs, from which cracks are generated in the ceramic substrate layer.

[0205] The sixth embodiment of the wiring substrate formed by the use ofthe transfer material of the present invention is a laminated structure.As shown in FIG. 15, similar to the wiring substrate of the third orfourth embodiment, a laminated structure includes electric insulatingsubstrates 1801 and 1802 formed of a ceramic and an electric insulatingsubstrate 1807 formed of at least one thermosetting resin composition.And the electric insulating substrate 1807 including a thermosettingresin is formed on at least a top layer or a bottom layer, and theelectric insulating substrates 1801 and 1802 including a ceramic areformed in inside layers. According to this structure, since the layercovering the outermost surface of the substrate is formed of thethermosetting resin composition that is not likely to be cracked, it isexcellent in falling resistant property.

[0206] In the production method for producing these dissimilar wiringsubstrates, by transferring the wiring pattern such as a copper foil,etc. to a green sheet or an uncured thermosetting resin impregnatedsheet, each wiring substrate is produced. Thus, a laminate having a lowresistance wiring in all layers can be obtained without being damaged atthe time of laminate.

[0207] Needless to say, after a wiring pattern is formed on a ceramicgreen sheet filled with via paste by a printing method or firing, thenan electrically insulating sheet containing a thermosetting resincomposition may be laminated onto the ceramic green sheet, therebyperforming an interlayer connection of the laminate. However, since thewiring pattern formed by a printing method becomes a projection, in aprocess of adhering the wiring pattern to the electrically insulatingsheet containing a thermosetting resin composition, stress concentrationoccurs, from which cracks are generated in the ceramic substrate layer.

[0208] Moreover, it is also possible to form circuit components such asan inductor, a capacitor, a resistor, a semiconductor device, or thelike, with electrically connected to the wiring pattern of the transfermaterial of this embodiment and to transfer them to the substratetogether with the wiring pattern. It is preferable that the passivecomponents such as inductor, capacitor, and resistor, etc. are formed onthe substrate by a printing method, for example a screen printingmethod.

[0209] Next, the further specific Examples of the first to fourthembodiments are explained hereinafter.

EXAMPLE 1

[0210] A first transfer material of the present invention was producedby a process shown in FIGS. 4A to 4F.

[0211] As shown in FIG. 4A, an electrolytic copper foil having athickness of 35 μm was prepared as a first metal layer 401. First, acopper salt raw material was dissolved in an alkaline bath and allowedto be electro-deposited on a rotation drum so that it had a highelectric current density. Thus, a metal layer (copper layer) was formedand this copper layer was rolled up continuously so as to form anelectrolytic copper foil.

[0212] Next, as shown in FIG. 4B, a Ni—P alloy layer was formed in athickness of about 100 nm as a peel layer 402 on the surface of thefirst metal layer 401 by plating. The electrolytic copper foil same asthe first metal layer 401 was laminated thereon in a thickness of 9 μmas a second metal layer for forming wiring pattern 403 by electrolyticplating. Thus, a three-layered structure laminate was produced.

[0213] The surface of the laminate was subjected to a rougheningtreatment so that the average roughness (Ra) of the center line of thesurface was about 4 μm. The roughening treatment was carried out byprecipitating fine copper powder on the electrolytic copper foil.

[0214] Next, as shown in FIGS. 4C to 4E, a dry film resist (DFR) 404 wasplaced by a photolithography method, and exposure and development of thewiring pattern portion was carried out. The first metal layer 403, thepeel layer 402 and the surface portion of the first metal layer 401 ofthe laminate were etched by a chemical etching process (immersing in anaqueous solution of ferric chloride) so as to form a desired wiringpattern.

[0215] Thereafter, as shown in FIG. 4F, the first transfer material wasobtained by removing a mask portion (DFR404) with a peeling material.Since the first metal layer and the second metal layer are formed of thesame materials, not only the second metal layer but also the surfacelayer of the first metal layer can be etched in a wiring pattern in oneetching process. This first transfer material has a structural featurein that the surface layer portion of the first metal layer that is acarrier layer is also processed in the wiring pattern.

[0216] In the produced first transfer material, the peel layer 402adhering the first metal layer 401 and the second metal layer 403 isweak in adhesive strength itself but excellent in etch resistanceproperty. Thus, even if the entire laminate of the first metal layer401, the peel layer 402, and the second metal layer 403 are subjected tothe etching process, interlayer portions are not peeled off and thewiring pattern can be formed without problems. On the other hand, theadhesive strength between the first metal layer 401 and the second metallayer 403 was 40 N/m (gf/cm), exhibiting an excellent peeling property.When the second metal layer 403 was transferred to the substrate byusing such a first transfer material, the adhesive plane between thesecond metal layer 403 and the peel layer 402 was peeled off easily, sothat only the second metal layer 403 was transferred to the substrate.

[0217] Since the first transfer material according to the presentinvention includes a carrier (first metal layer) formed of a copper foilhaving a thickness of 35 μm, even if the transfer material is deformedat the time of transfer, the carrier layer was resistant to thedeformation stress.

[0218] In the first transfer material of the first metal layer that is acarrier layer, the wiring pattern is a convex portion and the portionexcluding the wiring pattern is a concave portion. Therefore, when thetransfer material is pressed onto the base material sheet (material forthe substrate), the base material extruded from the portion into whichthe wiring pattern is embedded is likely to flow into the concaveportion, thus suppressing the deformation stress that distorts thepattern in the vertical direction. Therefore, the distortion of thepattern in this Example was only the amount generated by the curing andshrinking of the base material (0.08%).

[0219] As a comparative example, by using a transfer material on whichthe surface layer of the first metal layer 401 is not etched at all andonly the second metal layer is formed into the wiring pattern (that is,a transfer material including a carrier layer having a flat surface),the wiring layer was transferred to the base material sheet. Thedistortion of the wiring pattern was at most 0.16%. In this comparativeexample, since the carrier is a thick copper foil, basically thedistortion is small as in Example 1. However, it was confirmed that inthe portion in which the wiring patterns are concentrated, the wiringpattern is somewhat distorted because the concave portion into whichbase material flows is small. The distortion amount of the pattern issubstantially small. However, when the transfer material according tothe comparative example is used, unlike the first transfer material ofthe present invention, a surface of the wiring pattern is on the sameplane or convex shape with respect to the surface of the substrate, butis not concave. Therefore, the effect of facilitating the positioning atthe time of flip chip mounting of the transfer material of the presentinvention cannot be exhibited. This shows the effect of the transfermaterial of the present invention in which the convex portioncorresponding to the wiring pattern is formed on the surface of thecarrier layer by etching also the first metal layer that is a carrierlayer.

[0220] In Example 1, for example, a Ni-plating layer, anickel-phosphorous alloy layer, an aluminum plating layer, or the like,having a thickness of 200 nm or less, is used as the peel layer.However, the peel layer is not necessarily limited thereto, and anyorganic layers can be used. An example of the organic layer includes,for example, a long chain aliphatic carboxylic acid that can be bondedto, for example, Cu and that is in a solid state at room temperature. Byusing this, the same effect as the transfer material of this example canbe realized.

EXAMPLE 2

[0221] A second transfer material of the present invention was producedby a process shown in FIGS. 5A to 5E by a production method differentfrom Example 1. The second transfer material is different from the firsttransfer material according to Example 1 in the structure of the firsttransfer material and the wiring layer.

[0222] First, an electrolytic copper foil having a thickness of 35 μmwas prepared as a first metal layer 501. A copper salt raw material wasdissolved in an alkaline bath and allowed to be electrodeposited to arotation drum so that it had a high electric current density. Thus, ametal layer (copper layer) was formed and this copper layer was rolledup continuously so as to form an electrolytic copper foil.

[0223] Next, a peel layer 502 formed of a thin nickel plating layer wasformed in a thickness of 100 nm or less on the surface of the firstmetal layer 501 formed of the electrolytic copper foil. The electrolyticcopper foil that is the same as the first metal layer 501 was laminatedthereon in a thickness of 3 μm as a second metal layer for formingwiring pattern 503 by electrolytic plating. Thus, a three-layeredlaminate including the first metal layer 501, the peel layer 502 and thesecond metal layer 503 was produced.

[0224] The surface of the second metal layer 503 of the laminate wassubjected to a roughening treatment, so that the average roughness (Ra)of the center line of the surface was about 3 μm. The rougheningtreatment was carried out by precipitating fine copper powder on theelectrolytic copper foil. Furthermore, an adhesive material (not shown)was coated and a dry film resist (DFR) 504 used for the photolithographywas placed thereon. The DFR 504 has a plating resistant property andserves as a plating resist. With the above-mentioned process, a laminateshown in FIG. 5A was produced.

[0225] Next, as shown in FIG. 5B, the DFR 504 of the wiring pattern wasexposed and developed so as to form a concave portion reaching thesecond metal layer 503 in a wiring pattern region of the DFR 504. Thedepth of the concave portion was 25 μm. Thereafter, as shown in FIG. 5C,a third metal layer 505 was formed of a copper plating layer having athickness of 20 μm in the concave portion by plating with anelectrolytic copper; and then the laminate was immersed in the peelingsolution so as to remove the DFR 504.

[0226] Finally, as shown in FIG. 5E, the patterning was carried out by achemical etching process by immersing the laminate in an aqueoussolution of ferric chloride. This etching process was carried out inorder to remove the thin second metal layer 503 having a thickness of 3μm and peel layer 502 (plating layer). As a result, the etching processwas carried out for a short time, also the third metal layer 505 waspartially etched so as to have a thickness of about 15 μm, andfurthermore, the surface of the first metal layer 501 also was erodedpartially. Thus, as shown in FIG. 5E, the second transfer material wasproduced.

[0227] Since the first, second and third metal layers are formed of thesame materials, i.e., copper, not only the second and third metal layersbut also a part of the first metal layer can be removed by one etchingprocess. Thus, a part excluding the wiring pattern on the surfaceportion of the first metal layer was formed into a concave portion.Furthermore, similar to Example 1, since the surface of the first layer,i.e. a carrier layer, was etched, and the third metal layer was formedby an additive method, the thickness can be controlled arbitrarily.Furthermore, in Example 2, the peel layer is not limited to a platinglayer, and an extremely thin adhesive layer formed of an organic layeror a sticking agent layer may be employed.

[0228] In the thus produced second transfer material, the peel layer 502for connecting the first metal layer 501 to the metal layers 503 and 505for forming the wiring patterns is weak in adhesive strength itself butexcellent in etch resistance property. Thus, even if the four-layerstructured entire laminate shown in FIG. 5D is subjected to an etchingprocess, interlayer portions are not peeled off and the wiring patterncan be formed without problems.

[0229] On the other hand, the adhesive strength between the first metallayer 501 and the second metal layer 503 via the peel layer 502 is 30N/m (gf/cm), exhibiting an excellent peeling property. Thereby, withthis second transfer, after the second metal layer 503 as the wiringpattern, and the third metal layer 505 are transferred to the basematerial sheet (a material for the substrate), the portion between thesecond metal layer 503 and the peel layer can be peeled off easily withonly the wiring layer remained on the substrate. At this time, the peellayer formed of the peel layer 502 was attached to the side of the firstmetal layer 501, that is, a carrier.

[0230] Moreover, as shown in FIG. 5E, the produced second transfermaterial of this embodiment is pressed onto the base material sheet (amaterial for the substrate) including an uncured thermosetting resin andthermally cured, then the first metal layer is removed by a chemicaletching process, and thereby the wiring layer (the second metal layer503 and the third metal layer 505) may be transferred to the substrate.By controlling the etching time, it is possible to make the substratesurface including the wiring layer flat and to make the wiring layer aconcave shape with respect to the substrate surface.

[0231] In this Example, similar to Example 1, the carrier layer isformed of copper foil having a thickness of 35 μm, even if the basematerial was deformed at the time of transfer, the carrier layer wasresistant to the deformation stress. On the other hand, in the transfermaterial in Example 2, the concave portion of the first metal layer,that is, a carrier layer is secured to be as deep as 5 μm. This allowsthe base material of the portion into which the wiring layer is embeddedto flow toward the concave portion easily when the transfer material ispressed onto the base material sheet and to suppress the deformationstress that distorts the pattern in the vertical direction.

[0232] Therefore, when the transfer material according to this Examplewas used, the distortion of the pattern in this Example was only theamount generated by the curing and shrinking of the base material(0.08%). This shows the effect that the surface portion of the firstmetal layer that is a carrier layer is etched so as to form the wiringpattern to be a convex shape and to form the portion excluding thewiring pattern to be a concave portion. Furthermore, when the wiringresistance after transfer was measured, as compared with Example 1, across sectional area for the wiring can be increased and reduce theresistance value by about 20 to 30% because the thickness of the wiringpattern was increased by the third metal layer.

[0233] In this Example, as shown in FIG. 5E, after the patterning of thefirst metal layer was carried out by a chemical etching process,transfer was carried out. However, the transfer may be carried out withcuring the base material by using the transfer material without chemicaletching process. However, in this case, after the transfer, the peelinglayer and the first metal layer are peeled off, and then the secondmetal layer is removed by a soft etching process etc., and thus thewiring pattern including only a third metal layer can be formed.

[0234] Furthermore, also in this case, the carrier copper foil (firstmetal foil) including a convex wiring pattern can be reused aftertransfer. Furthermore, the wiring pattern transferred to the substrateby using the transfer material of this Example has a concave portionwith respect to the substrate surface. This concave portion can be usedfor positioning, e.g. facilitates the flip-chip mounting of a bare chip.

EXAMPLE 3

[0235] A transfer material according to this Example is another exampleof the second transfer material. The transfer material of this Exampleis different from that of Example 2 in the structure of the wiringlayer, however, the drawing is the same, and the transfer material ofthis Example is described with reference to FIGS. 5A to 5E.

[0236] First, an electrolytic copper foil having a thickness of about 35μm was prepared as a first metal layer 501. A copper salt raw materialwas dissolved in an alkaline bath and allowed to be electrodeposited ona rotation drum so that it had a high electric current density. Thus, ametal layer (copper layer) was formed. This copper layer was rolled upcontinuously so as to form an electrolytic copper foil.

[0237] Next, a peel layer 502 formed of a thin nickel plating layerhaving a thickness of 100 nm or less was formed on the surface of thefirst metal layer 501. The electrolytic copper foil same as the firstmetal layer 501 was laminated thereon in a thickness of 3 μm as a secondmetal layer for forming wiring pattern 503 by electrolytic plating.Thus, a three-layered laminate including the first metal layer 501, thepeel layer 502 and the second metal layer 503 was produced.

[0238] The surface of the laminate was subjected to a rougheningtreatment so that the average roughness (Ra) of the center line of thesurface was about 3 μm. The roughening treatment was carried out byprecipitating fine copper powder on the electrolytic copper foil.Furthermore, an adhesive material that was the same as in Example 2 wascoated and a dry film resist (DFR) 504 used for the photolithography wasplaced thereon. The DFR 504 has a plating resistant property and servesas a plating resist. Thus, as shown in FIG. 5A, a four-layered laminatewas produced.

[0239] Next, as shown in FIG. 5B, the DFR 504 of the wiring pattern wasexposed and developed so as to form a concave portion that reaches thesecond metal layer 503 in a region corresponding to the wiring patternin the DFR 504. The depth of the concave portion is 25 μm. Thereafter,as shown in FIG. 5C, a third metal layer 505 formed of a copper platinglayer having a thickness of 2 μm was formed. Then, as shown in FIG. 5D,the laminate was immersed in a peeling solution so as to remove the DFR504.

[0240] Finally, as shown in FIG. 5E, the patterning was carried out by achemical etching process by immersing the laminate in an aqueoussolution of ferric chloride. This etching process is different from thatof Example 2 in that a gold plating layer 505 serves as an etchingresist, so that it is possible to remove selectively the thin secondmetal layer 503 having a thickness of 3 μm and the thin peel layer 502.As a result, since a transfer material whose top layer is gold platedwas obtained, the surface of the wiring pattern may not be oxidized.Therefore, when a bare chip or a component is mounted on the wiringpattern after the wiring pattern is formed on the substrate by using thetransfer material, it is possible to attain a low resistance connection.

[0241] Furthermore, as a comparative example, a gold plated transfermaterial was produced by plating gold on the entire surface of thetransfer material having a wiring formed of single layered copper foilwiring, as shown in FIG. 1. When the gold plated transfer material wasexamined for transferring property, the transferring property of thewiring pattern was damaged. This shows the effect of the transfer ofthis Example on which a gold plating layer is formed only on the surfacelayer of the wiring pattern.

EXAMPLE 4

[0242] A third transfer material of the present invention was producedas shown in FIGS. 6A to 6E. The third transfer material is the same atthe second transfer material according to Example 2 or 3 of the presentinvention except the structure of the wiring layer.

[0243] First, as shown in FIG. 6A, a four-layered laminate including afirst metal layer 601, a peel layer 602, a second metal layer 603 anddry film resist (DFR) 604 was prepared. Since the structure and themethod for producing this laminate are the same as the laminate shown inFIG. 4C in Example 1, the explanation is not repeated herein.

[0244] Next, as shown in FIG. 6B, a region 607 excluding a regioncorresponding to the wiring pattern in the DFR 604 was exposed anddeveloped so as to form a concave portion 608 having a thickness of 25μm corresponding to the thickness of the DFR 604 was formed in theregion of the wiring pattern. Thereafter, as shown in FIG. 6C, a copperplated layer (third metal layer) 605 having a thickness of 15 μm wasformed by electroless copper plating in a deposition thickness of about2 μm followed by electrolytic copper plating. In this Example, further asilver plating layer (fourth metal layer 606) was deposited thereon byelectrolytic silver plating to a thickness of about 3 μm.

[0245] Next, similar to Example 2, as shown in FIG. 6D, the laminate wasimmersed in a peeling solution so as to remove the DFR. Finally, asshown in FIG. 6E, the patterning was carried out by a chemical etchingprocess by immersing the laminate in an aqueous solution of ferricchloride. This etching process was carried out basically in order toremove the thin second metal layer 603 having a thickness of 3 μm.However, since the fourth metal layer 606 that is a silver plating layerserves as an etching mask, the third metal layer 605 and the fourthmetal layer 606 are not substantially etched except for a small sideetching portion, so that the thickness is maintained. Furthermore, thisetching process is continued until the peel layer 602 and the surfaceportion of the first metal layer 601 were corroded.

[0246] Also in this Example, short-time etching is sufficient for thepatterning of the second metal layer 603, etc. Thus, the third transfermaterial was obtained, in which a region excluding the wiring pattern onthe surface layer portion of the first metal layer 601 was formed in aconcave shape. By adjusting the etching time, it is possible to controlthe depth of the concave portion of the first metal layer 601 freely.

[0247] Since the first, second and third metal layers are formed of thesame material, copper, not only the second and third metal layers butalso a part of the first metal layer is corroded by one chemical etchingprocess. Thus, a part excluding the wiring pattern on the surface layerportion of the first metal layer could be formed into a concave portion.Furthermore, similar to Example 1, in the third transfer materialaccording to this Example, the surface of the first layer that is acarrier layer was etched. The fourth metal layer (silver plating layer)that is different from the second and third metal layers (copper platinglayers) is further formed by an additive method.

[0248] In the thus produced third transfer material, the peel layer 602adhering the first metal layer 601 as a carrier layer to the secondmetal layer 603 as a wiring layer, a third metal layer 605 and thefourth metal layer 602 is weak in adhesive strength itself but excellentin etch resistance property. Thus, even if the entire five-layeredlaminate shown in FIG. 6D is subjected to an etching process, only thesecond metal layer 603 can be removed effectively and the transfermaterial can be formed without peeling off the interlayer portion of thelaminate. The adhesive strength between the first metal layer 601 andthe second metal layer 603 via the peel layer 602 was 40 N/m (gf/cm),exhibiting an excellent peeling property.

[0249] With such a third transfer, a three-layered wiring patternincluding the second metal layer 603, the third metal layer 605 andfourth metal layer 606 was transferred to the base material sheet (amaterial for the substrate). As a result, an adhesive plane (peel layer602) between the first metal layer 601 and the second metal layer 603was peeled off easily and the three-layered wiring pattern wastransferred to the base material.

[0250] In this Example, similar to Example 1, the carrier layer wasformed of copper foil having a thickness of 35 μm, and even if thetransfer material was deformed at the time of transfer, the carrierlayer was resistant to the deformation stress. On the other hand, in thetransfer material in this example, the concave portion of the firstmetal layer that is a carrier layer is secured to be as deep as 10 μm.Therefore, when the transfer material is pressed onto the base materialsheet, the base material extruded from the portion into which the wiringpattern is embedded is likely to flow into the concave portion, thussuppressing the deformation stress that distorts the pattern in thevertical direction.

[0251] Therefore, similar to Example 2, the distortion of the pattern inthis Example was only the amount generated by the curing and shrinkingof the base material (0.07%). This shows the effect of forming theconcave and convex portion in accordance with the wiring pattern also inthe first metal layer that is a carrier layer. Furthermore, when thewiring resistance after transfer was measured, as compared with Example1, because the thickness of the wiring pattern was increased by thethird metal layer, a cross sectional area for the wiring can beincreased and reduce the resistance value by about 20 to 30%.

[0252] Furthermore, in this Example, since the outermost layer that isin contact with the base material in the wiring layer is formed of asilver plating layer, it was possible to stabilize the connectingproperty between the wiring pattern and the conductive via pastementioned below in Example 5.

[0253] Furthermore, when the wiring pattern is formed on the substrateby using the transfer material of this Example, similar to theabove-mentioned Examples, the concave shaped wiring pattern cancontribute to the positioning in a flip chip mounting. Furthermore, itis needless to say that the carrier copper foil (first metal layer) onwhich the convex portion corresponding to the wiring pattern can bereused after transfer.

EXAMPLE 5

[0254] A composite wiring substrate was produced by using the thirdtransfer material formed in Example 4 as shown in FIGS. 7A to 7C. InFIGS. 7A to 7C, a metal layer 701 corresponds to the fourth metal layer606 of the third transfer material according to Example 4, a metal layer702 corresponds to the third metal layer 605 of the third transfermaterial, a metal layer 703 corresponds to the second metal layer 603 ofthe third transfer material, a metal layer 704 corresponds to the peellayer 602 of the third transfer material, and a metal layer 705corresponds to the first metal layer 601 of the third transfer material,respectively.

[0255] First, a substrate to which the wiring pattern is to betransferred was prepared. This substrate was produced by preparing thebase material sheet 706 formed of composite materials shown below,providing the base material sheet with via holes, and filling the viaholes with a conductive paste 707. Hereinafter, the componentcompositions of the base material sheet 706 are described.

[0256] (Component Composition of the Base Material Sheet 706)

[0257] Al₂O₃ (AS-40 manufactured by Showa Denko K. K., average particlediameter of 12 μm) 90 weight %

[0258] liquid epoxy resin (EF-450 manufactured by Nippon Rec Co. Ltd.)9.5 weight %

[0259] carbon black (manufactured by Toyo Carbon) 0.2 weight %

[0260] coupling agent (46B, titanate based coupling agent manufacturedby Ajinomoto Co., Inc.) 0.3 weight %

[0261] Each of the above-mentioned components was weighed so as to havethe above-mentioned composition weight ratio. A solvent of methyl ethylketone was added into the mixture of the above-mentioned components sothat the viscosity of the slurry mixture was about 20 Pa.s, and thenrotated and mixed by the use of alumina balls in a pot at the rotationrate of 500 rpm for 48 hours so as to form into a slurry.

[0262] Next, as a mold release film, a PET film having a thickness of 75μm was prepared. On the PET film, the slurry was formed into a filmsheet at a gap of about 0.7 mm by a doctor blade method. The film sheetwas allowed to stand for 1 hour at 100° C. so as to volatilize themethyl ethyl ketone solvent and to remove the PET film, thus to forminto a base material sheet 706 having a thickness of 350 μm. Since thesolvent was removed at 100° C., the epoxy resin was kept to be uncuredand the base material sheet 706 had a flexibility.

[0263] This base material sheet 706 was cut in a predetermined size bythe use of its flexibility, and provided with through holes (via holes)having a diameter of 0.15 mm at equal intervals with a pitch of 0.2 to 2mm. Then, the through holes were filled with a conductive paste forfilling via holes 707 by a screen printing method. Thus, the substratewas produced. The conductive paste 707 to be used was obtained by mixingand kneading the following materials at the below mentioned compositionsby the use of a triple roller.

[0264] [Component Composition of the Conductive Paste 707]

[0265] spherical copper particles (Mitsui Mining & Smelting Co., Ltd.,particle diameter of 2 μm) 85 weight %

[0266] bisphenol A epoxy resin (Epicoat 828 manufactured by Yuka ShellEpoxy) 3 weight %

[0267] glycidyl ester based epoxy resin (YD-171 manufactured by TotoKasei) 9 weight %

[0268] amine adduct hardening agent (MY-24 manufactured by AjinomotoCo., Inc.) 3 weight %

[0269] Next, as shown in FIG. 7A, the third transfer material was placedso that the side of the fourth metal layer 701 of the third transfermaterial was in contact with both surfaces of the base material sheet706, and heated and pressed by a thermal press treatment at a pressureof 9.8×10⁵ Pa (10 kgf/cm²) at a pressing temperature of 120° C. for 5minutes. With this heating and pressing treatment, an epoxy resin in thebase material sheet 706 and the conductive paste 707 was fused andsoftened. Thus, the wiring pattern including the second, third, andfourth metal layers 703, 702 and 701 was allowed to be embedded in thebase material sheet 706.

[0270] Then, the epoxy resin was cured by raising the heatingtemperature and treated at 175° C. for 60 minutes. This led to strongconnection between the base material sheet 706 and the second, third,and fourth metal layers 703, 702 and 701. Furthermore, the conductivepaste 707 and the fourth metal layer 701 were electrically connected(inner via connection) and strongly adhered to each other.

[0271] From the laminate shown in FIG. 7B, the first metal layer 705(carrier layer) and the peel layer 704 were peeled off together. Thus,the wiring substrate as shown in FIG. 7C including the second, third andfourth metal layers 703, 702 and 701 transferred to both surfaces wasobtained. This wiring substrate is referred to as a wiring substrate 7A.This wiring substrate 7A is provided with the concave portioncorresponding to the depth of the concave portion formed by etchingprocess on the surface layer portion of the first metal layer 705. Atthe bottom of the concave portion, the second, third, and fourth metallayers 703, 702 and 701 were formed.

[0272] Furthermore, besides the wiring substrate 7A produced in thisExample, a wiring substrate (referred to as a wiring substrate 7B) alsois produced by transferring the wiring pattern by using the firsttransfer material described in Example 1. In order to evaluate thereliability of the thus wiring substrates 7A and 7B, a solder reflowtest and a temperature cycling test were performed. The following arethe methods of each test.

[0273] [Solder Reflow Test]

[0274] The solder reflow test was performed with a belt type reflowtester (manufactured by Matsushita Electric Industrial Co., Ltd.) inwhich a 10 second cycle was repeated 10 times at a maximum temperatureof 260° C.

[0275] [Temperature Cycling Test]

[0276] The temperature cycle test was performed by allowing the wiringsubstrate to stand at 125° C. for 30 minutes and then at −60° C. for 30minutes per cycle, and repeating this cycle for a total of 200 cycles.

[0277] In either the solder reflow test or the temperature cycle test,no cracks were generated in the wiring substrates 7A and 7B, andabnormality was not recognized, even if a supersonic flaw detector wasused. A resistance value of the inner via connection by the conductiveresin paste 707 was not substantially changed between measurements madebefore and after the tests.

[0278] The initial performance was hardly changed before and after thetests, however, the change rate was 5% or less in the wiring substrate7A, while the change rate was 10% or less in the wiring substrate 7B.Both via connections of the wiring substrates had a sufficientstability, however, in the wiring substrate 7A in which Ag plating layeris present in the connecting portion between the wiring layer and theconductive resin paste, more stable via connection could be realized.

EXAMPLE 6

[0279] A ceramic wiring substrate as shown in FIG. 8 was produced byusing the transfer material produced in Example 1.

[0280] First, a substrate to which the wiring pattern is to betransferred was prepared. This substrate was produced by preparing a lowtemperature sintering ceramic green sheet 805 including a lowtemperature sintering ceramic material and an organic binder, providingthis green sheet with via holes, and filling the via holes withconductive paste 806. Hereinafter, the component compositions of thegreen sheet 805 are described.

[0281] (Component Composition of the Green Sheet 805)

[0282] mixture of ceramic powder Al₂O₃ and borosilicate glass (MLS-1000manufactured by Nippon Electric Glass Co., Ltd.) 88 weight %

[0283] methacrylic acid based acrylic binder (Olicox, manufactured byKyoeisya Kagaku Co., Ltd.) 10 weight %

[0284] BBP (manufactured by Kanto Chemical Co., Inc.) 2 weight %

[0285] Each of the above-mentioned components is weighed so as to havethe above-mentioned composition weight ratio. A solvent of toluene wasadded into the mixture of the above-mentioned components so that theviscosity of the slurry mixture was about 20 Pa.s, and then rotated andmixed by the use of alumina balls in a pot at the rotation rate of the500 rpm for 48 hours so as to form into a slurry.

[0286] Next, as a mold release film, a polyphenylene sulfide (PPS) filmhaving a thickness of 75 μm was prepared. On the PPS film, the slurrywas formed into a film sheet at a gap of about 0.4 mm by a doctor blademethod. The toluene solvent in the sheet was allowed to be volatilizedso as to remove the PES film, thus to form a green sheet 805 having athickness of 220 μm. Since in this green sheet 805, a plasticizer BBPwas added into the methacrylic acid based acrylic binder, flexibilityand excellent thermal decomposition property were exhibited.

[0287] This green sheet 805 was cut in a predetermined size by makinguse of its flexibility, and provided with through holes (via holes)having a diameter of 0.15 mm at equal intervals with a pitch of 0.2 mmto 2 mm by the use of a punching machine. Then, the through holes werefilled with a conductive paste for filling via holes 806 by a screenprinting method. Thus, the substrate was produced. The conductive paste806 to be used was obtained by mixing and kneading the followingmaterials at the following compositions by the use of a triple roller.

[0288] [Component Composition of the Conductive Paste 806]

[0289] spherical silver particles (Mitsui Mining & Smelting Co., Ltd.,particle diameter of 3 μm) 75 weight %

[0290] acrylic resin (manufactured by Kyoeisya Kagaku Co., Ltd.,polymerization degree 100 cps) 5 weight %

[0291] borosilicate glass (manufactured by Nippon Electric Glass Co.,Ltd) 3 weight %

[0292] terpineol (manufactured by Kanto Chemical Co., Inc.) 12 weight %

[0293] BBP (manufactured by Kanto Chemical Co., Inc.) 5 weight %

[0294] Next, the first transfer material produced in Example 1 wasplaced so that the side of the second metal layer (wiring layer) was incontact with both surfaces of the substrate, heated and pressed by athermal press treatment at a pressing temperature of 70° C. and at apressure of about 5.88×10⁶ Pa (60 kgf/cm²) for 5 minutes. With thisheating and pressing treatment, an acrylic resin in the substrate wasfused and softened. Thus, the second metal layer (wiring layer), a peellayer, and a part (concave portion) of the first metal layer (carrier)of the first transfer material were embedded into the substrate.

[0295] After the laminate was cooled, the first metal layer (carrier)and a peel layer were peeled off from the laminate, and thereby only thesecond metal layer remained. As shown in FIG. 8, a wiring substrate 800having a wiring layer 801 formed of a second metal layer is formed onboth surfaces of the substrate was obtained.

[0296] Then, an alumina green sheet that is not sintered at the firingtemperature was laminated on both surfaces of the wiring substrate andfixed, by carrying out the binder removing process and firing in anatmosphere of nitrogen. First, in order to remove the organic binder inthe green sheet 805, the laminate was heated by the use of an electricfurnace in nitrogen up to 700° C. while raising temperatures at the rateof 25° C./hour, and treated at 700° C. for 2 hours. Then, the wiringsubstrate in which the binder was removed was burned by treating innitrogen at 900° C. for 20 minutes. The firing condition was set to be atemperature rising time of 20 minutes, temperature falling time of 20minutes and in/out total time of 60 minutes. After firing, the aluminagreen sheet was easily removed. Thus, a low temperature sinteringceramic wiring substrate 800 was produced.

[0297] On both surfaces of the wiring substrate 800, the concave portioncorresponding to the depth of the convex and concave of the first metallayer of the first transfer material was formed, and the wiringsubstrate 801 including the second metal layer was formed at the bottomof the concave portion. Furthermore, the surface wiring layers 801 onthe both surfaces were electrically connected to each other with aconductive metal sintering via that is formed by sintering theconductive paste 806 in the thickness direction. In the configuration ofthis Example, as shown in FIG. 8, a gold plating layer 802 was formed onthe second metal layer 801 of the wiring substrate 805.

[0298] Next, a configuration on which a bare semiconductor chip 905 wasflip-chip mounted on the surface of the low temperature sinteringceramic substrate 800 is explained. FIG. 9 is a cross sectional viewshowing one example of the schematic configuration in which a baresemiconductor chip 905 was flip-chip mounted on the surface of the lowtemperature sintering ceramic substrate 800.

[0299] First, a projecting bump 903 produced by a gold wire bonding wasformed on an aluminum pad 904 on the surface of the bare semiconductorchip 905, and thermosetting conductive adhesive agent (not shown) wastransferred on the bump 903. By adhering the projecting bump 903 to thegold plating layer 802 via a conductive adhesive agent while positioningthe projecting bump 903 with respect to the concave portion (wiringpattern portion) of the ceramic wiring substrate 800, the semiconductordevice 905 was mounted. Consequently, as mentioned above, in the concaveportion formed by transferring the second metal layer (wiring layer 801)by using the first transfer material, the bump 903 and the wiring layer(second metal layer 801 and gold plating layer 802) were connected.

[0300] In order to evaluate the reliability of the flip-chip mountedsubstrate, a solder reflow test and a temperature cycling test werecarried out. Each test was carried out under the same conditions as inExample 4. As a result, a resistance value of the bump connection in theceramic wiring substrate 800 on which the semiconductor device 905 wasflip-chip mounted was not substantially changed between measurementsmade before and after the tests and exhibited the stability.

[0301] When the transfer material shown in FIG. 2 having the secondmetal layer formed of Ag plating layer and the third metal layer formedof Ag pattern plating layer was transferred, it was possible to transferthe Ag plating wiring pattern to the ceramic green sheet 805. In thiscase, in the production process, since binder removing process andfiring treatment can be carried out in the air, it is advantageous fromthe viewpoint of cost. Furthermore, oxidation resistance property isremarkably improved.

EXAMPLE 7

[0302] A multi-layered wiring substrate was produced by using a transfermaterial and a substrate formed of a composite material produced by thesame method as in Example 5. FIG. 10 is a cross-sectional view showingone example of a schematic configuration of the multi-layered wiringsubstrate.

[0303] As shown in FIGS. 10A to 10J, reference numerals 1001 a, 1001 band 1001 c denote substrate sheets; 1002 a, 10002 b and 1002 c denotefirst metal layers that are carriers; 1003 a, 1003 b and 1003 c denoteconductive pastes; 1004 a, 10004 b and 1004 c denote second metal layersserving as a wiring pattern; 1005 a, 1005 b and 1005 c denote peellayers; A, B, C and D denote transfer materials, and E denotes amulti-layered substrate, respectively.

[0304] Furthermore, in FIGS. 10A to 10I, FIGS. 10A, 10D and 10G show thesteps for producing a single layered wiring pattern by using thetransfer material A and the substrate 1001 a; similarly, FIGS. 10B, 10Eand 10H show the steps for producing a single layered wiring pattern-byusing the transfer material B and the substrate 1001 b; and FIGS. 10C,10F and 10I show the steps for producing a single layered wiring patternby using the transfer materials C and D and the substrate 1001 c;respectively. Furthermore, FIG. 10J shows a multi-layered wiringsubstrate E produced by laminating the above-mentioned three singlelayered substrates. Unless otherwise noted, each single wiring substrateis produced by the same method as in Example 5.

[0305] First, the transfer materials A, B, C, and D shown in FIGS. 10A,10B, and 10C were produced. First, electrolytic copper foils having athickness of 35 μm were produced as the first metal layers 1002 a, 1002b, 1002 c, and 1002 d by the same method for producing foils as inExample 1.

[0306] Next, the peel layers 1005 a, 1005 b, 1005 c and 1005 d made of aNi—P alloy plating layer were formed thinly on the roughened surface ofthe first metal layers 1002 a, 1002 b, 1002 c, and 1002 d to thethickness of 100 nm or less. Electrolytic copper foils having athickness of 9 μm as the second metal layers for forming wiring patterns1004 a, 1004 b, 1004 c, and 1004 d were laminated thereon by the sameelectrolytic plating as in Example 1 so as to form a three-layeredlaminate. Herein, as the peel layer, a chrome plating layer can be used.

[0307] Next, an etching process using a base copper chloride aqueoussolution capable of removing only copper was carried out from the sideof the second metal layers for forming wiring patterns 1004b and 1004 cso as to form the second metal layers 1004 b and 1004 c into desiredwiring patterns. Thus, transfer materials B, C shown in FIGS. 10B and10C were obtained. Similarly, an etching process with respect to copperand the Ni—P alloy plating layer was carried out by a chemical etchingprocess from the side of the second metal layers for forming wiringpatterns 1004 a and 1004 d so as to form the second metal layers 1004 aand 1004 d into desired wiring patterns. At the same time, a convex andconcave portion corresponding to the wiring pattern was formed on thesurface portion of the first metal layer 1002 a and 1002 d. Moreover,the convex portion corresponds to a region of the wiring patterns, andthe concave portion corresponds to a region excluding the wiringpatterns. Thus, transfer materials A, D shown in FIGS. 10A and 10C wereobtained.

[0308] Next, as shown in FIGS. 10A, 10B, and 10C, the second metallayers 1004 a, 1004 b and 1004 c of the transfer materials A, B, C, andD were placed so that the side of the second metal layers 1004 a, 1004 band 1004 c were in contact with the surfaces of the substrate sheets1001 a, 1001 b and 1001 c. In FIG. 10C, the transfer materials C and Dwere placed, respectively on both surfaces of the substrate sheet 1001c.

[0309] Then, as shown in FIGS. 10D, 10E, and 10F, the laminates of thetransfer materials A, B, C and D and the substrates 1001 a, 1001 b and1001 c were heated and pressed at a temperature of 100° C., and at apressure of about 9.8×10⁵ Pa (10 kgf/cm²) for 5 minutes and epoxy resinin the substrate sheets 1001 a, 1001 b, 1001 cwas fused and softened.Thus, the second, third, and fourth metal layers 1004 a, 1004 b, 1004 c,and 1004 d were embedded in the substrate sheets 1001 a, 1001 b, and1001 c, respectively.

[0310] Next, by peeling the first metal layers 1002 a, 1002 b, 1002 cand 1002 d from the laminate together with the peel layers 1005 a, 1005b, 1005 c , and 1005 d, only the second metal layers 1004 a, 1004 b,1004 c and 1004 d are remained on the substrate sheets 1001 a, 1001 band 1001 c. Thus, three kinds of single-layered wiring substrates, i.e.,a single-layered wiring substrate having a flat surface (FIG. 10H), asingle-layered wiring substrate having a concave portion on the wiringlayer portion (FIG. 10G), and a single-layered wiring substrate having aflat surface on one surface and the concave portion on another surface(FIG. 10I), were obtained.

[0311] Finally, as shown in FIG. 10J, the three kinds of single layeredwiring substrates were laminated, and then heated and pressed at atemperature of 175° C., and at a pressure of about 7.84×10⁶ Pa (80kgf/cm²) for one hour so as to allow the laminate to be thermally curedand shrunk. Thus, a multi-layered substrate E was obtained. With thisprocess, epoxy resin in the substrate sheets 1001 a, 1001 b, and 1001 cand the conductive paste 1003 a, 1003 b, and 1003 c were cured, so thatthe mechanical strength of the multi-layered wiring substrate E wasmaintained. Furthermore, the second metal layers 1004 a, 1004 b, 1004 cand 1004 d were electrically connected to each other with a conductiveresin via paste 1003 a, 1003 b, and 1003 c. Since the multi-layeredsubstrate E was allowed to be thermally cured and shrunk in one timeafter the single layered wiring substrates were laminated, there was novia deviation in a via-on-via structure.

[0312] The thus obtained multi-layered substrate E can form a finewiring pattern with a line width of about 50 μm. Furthermore, since ithad an IVH structure, it was useful as an extremely small and highdensity mounted wiring substrate. In particular, since the wiringpattern was transferred and formed by the use of the transfer materialaccording to the present invention, no dislocation occurs on the surfacelayer plane in which the fine wiring patterns are concentrated. Thus,the yield rate is expected to be improved.

[0313] Furthermore, the wiring layer on the surface layer on whichchips, etc. are mounted has a concave portion, and it was possible tocarry out the flip chip mounting easily. Moreover, the multi-layeredsubstrate of the present invention is not limited to the above-mentionedstructure. For example, a multi-layered wiring substrate having a singlelayered wiring substrate having a wiring layer provided with a concaveportion as mentioned above can be employed. The multi-layered substratein this case also shows a low resistant and high reliable viaconnection.

[0314] Furthermore, when the second metal layer is made of copper foil,a gold plating layer can be formed on the upper layer portion in orderto prevent oxidation. In this case, if the surface of the gold platinglayer also has a concave portion with respect to the substrate surface,it is possible to reduce the creeping distance even in a fine wiringpattern, and is advantageous from the viewpoint of preventing migration.

[0315] In this Example, the composite substrate was used. However, thebase material is not necessarily limited thereto and a ceramic greensheet can be used. In this case, a multi-layered substrate can beattained by the same process except only the sintering process in theproduction process explained in this Example.

[0316] Furthermore, in this Example, the first transfer materialincluding a wiring pattern made of the single layered metal layer wasused. However, by using the second or third transfer material, amulti-layered wiring substrate having a plurality of metal layers, canbe produced.

EXAMPLE 8

[0317] A multi-layered wiring substrate including a laminate made of aceramic substrate and a substrate including at least a thermosettingresin was produced by using the first transfer material explained inExample 1.

[0318] First, a base material sheet, which is a material for a ceramicwiring substrate 1608 (see FIG. 16B) and to which a wiring pattern istransferred, was prepared. This base material sheet was produced bypreparing a low temperature sintering ceramic green sheet including alow temperature sintering ceramic material and an organic binder,providing this green sheet with via holes, and filling the via holeswith conductive paste 1609. Hereinafter, the component compositions ofthe green sheet are described.

[0319] [Component Composition of the Green Sheet]

[0320] mixture of ceramic powder Al₂O₃ and borosilicate glass (MLS-1000manufactured by Nippon Electric Glass Co., Ltd) 88 weight %

[0321] methacrylic acid based acrylic binder (Olicox, manufactured byKyoeisya Kagaku Co., Ltd) 10 weight %

[0322] BBP (manufactured by Kanto Chemical Co., Inc.) 2 weight %

[0323] Each of the above-mentioned components was weighed so as to havethe above-mentioned composition weight ratio. A solvent of toluene wasadded into the mixture of the above-mentioned components so that theviscosity of the mixture slurry was about 20 Pa.s, and then rotated andmixed by the use of alumina balls in a pot at the rotation rate of the500 rpm for 48 hours so as to form a slurry.

[0324] Next, as a mold release film, a polyphenylene sulfide (PPS) filmhaving a thickness of b 75 μm was prepared. On the PPS film, the slurrywas formed into a film sheet at a gap of about 0.4 mm by a doctor blademethod. The toluene solvent in the sheet was allowed to be volatilizedso as to remove the PPS film, thus to form into a green sheet having athickness of 220 μm. Since in this green sheet, a plasticizer BBP wasadded into the methacrylic acid based acrylic binder, flexibility andexcellent thermal decomposition property were exhibited.

[0325] This green sheet was cut in a predetermined size by making use ofits flexibility, and provided with through holes (via holes) having adiameter of 0.15 mm at equally intervals with a pitch of 0.2 mm to 2 mmby the use of a punching machine. Then, the through holes were filledwith a conductive paste for filling via holes 1609 by a screen printingmethod. Thus, the base material sheet was produced. The conductive paste1609 to be used was obtained by mixing and kneading the followingmaterials at the following compositions by the use of a triple roller.

[0326] [Component Composition of the Conductive Paste 1609]

[0327] spherical silver particles (manufactured by Mitsui Mining &Smelting Co., Ltd., particle diameter of 3 μm) 75 weight %

[0328] acrylic resin (manufactured by Kyoeisya Kagaku Co., Ltd,polymerization degree 100 cps) 5 weight %

[0329] borosilicate glass (Nippon Electric Glass Co., Ltd) 15 weight %

[0330] BBP (manufactured by Kanto Chemical Co., Inc.) 5 weight %

[0331] Next, the first transfer material described in Example 1 wasplaced so that the side of the second metal layer was in contact withboth surfaces of the substrate, heated and pressed by a thermal presstreatment at a pressing temperature of 70° C. and at a pressure of about5.88×10⁶ Pa (60 kgf/cm²) for 5 minutes. With this heating and pressingtreatment, an acrylic resin in the substrate was fused and softened.Thus, the wiring layer (second metal layer), a peel layer, and a surfaceportion (concave portion) of the carrier (first metal layer) of thefirst transfer material were embedded into the substrate.

[0332] After the laminate is cooled, the carrier of the first transfermaterial was peeled off from the laminate together with a peel layer,thereby only the second metal layer was remained on the laminate. Asshown in FIG. 16B, a wiring substrate 1608 having a wiring layer 1610formed of a second metal layer is formed on both surfaces of thesubstrate was obtained.

[0333] Then, an alumina green sheet that is not sintered at the firingtemperature was laminated on both surfaces of the ceramic substrate1608, and fixed, by carrying out the binder removing process and firingin an atmosphere of nitrogen. First, in order to remove the organicbinder in the ceramic wiring substrate 1608, the laminate was heated bythe use of an electric furnace in nitrogen up to 700° C. while raisingtemperatures at the rate of 25° C./hour, and treated at 700° C. for 2hours. Then, the ceramic wiring substrate 1608 in which the binder wasremoved was burned by treating in nitrogen at 900° C. for 20 minutes.The firing condition was set to be a temperature rising time of 20minutes, temperature falling time of 20 minutes and in/out total time of60 minutes. After firing, the alumina green sheet was removed easily.

[0334] Furthermore, as shown in FIG. 16B, wiring substrates 1605, 1606,and 1607 made of composite materials were laminated as shown in FIGS.16A to 16C, with the ceramic wiring substrate 1608 that has beenproduced as mentioned above being sandwiched therebetween as shown inFIG. 16B. Thus, a laminate in which all layers were interlayer connectedwas obtained.

[0335] Herein, the method for producing the composite wiring substrate1605 etc. is described. As shown in the uppermost part of the FIGS. 16Aand 16B, by using the first transfer material 1601 (the same as inExample 1) according to the present invention, the wiring pattern formedon the first transfer material is transferred to an uncured compositesheet (having the same composition as in Example 5, so that asingle-layered wiring substrate 1605 having a wiring pattern 1604 isformed. The composite sheet 1602 is provided with thorough holes, andthe through holes are filled with a conductive,paste 1603. By the samemethod, the single-layered substrates 1606 and 1607 using the compositesheet 1602 are produced.

[0336] Thereafter, the composite single-layered wiring substrates 1605to 1607 were laminated on both surfaces of the ceramic wiring substrate1607, and subjected to the thermal press treatment at a pressingtemperature of 200° C. and a pressure of about 2.94×10⁶ Pa (30 kgf/cm²)for 60 minutes. With this heating and pressing treatment, an acrylicresin in the composite sheet 1602 in the single-layered wiringsubstrates 1605 to 1607 was fused and softened. Thus, the entire wiringsubstrate including the ceramic layer 1608 was cured and integrated intoone piece as shown in FIG. 16C.

[0337] By the same method as in this Example, a multi-layered wiringsubstrate including a composite wiring substrate and the ceramic wiringsubstrate was produced as shown in FIG. 11 or FIG. 12. The configurationis the same as that of the multi-layered wiring substrate shown in FIG.11 or FIG. 12.

[0338] When the multi-layered wiring substrate shown in FIGS. 11 and 12produced by a method of this Example was observed by the use of anX-ray, no damaged portions such as cracks were generated in the ceramiclayer.

[0339] In addition, when the via connection resistance was evaluated, itwas shown that the multi-layered substrate had a low resistant viaconnection.

[0340] As shown in FIG. 11, when the ceramic wiring substrate 1608 wasnot provided with the inner via holes and Ba—Ti—O ceramic was used for acapacitance layer, the high capacitance of 10 to 50 nF/cm² was realizedeasily.

[0341] Furthermore, an inner electrode layer may be formed on the resinsubstrate layer 1602 or may be formed in the ceramic layer 1608.

[0342] In addition, in this Example, the first transfer material wasused for producing the wiring layer of each single-layered wiringsubstrate. However, when the second or third transfer material may beused, it is also possible to produce multi-layered wiring substratehaving a wiring layer including a plurality of metal layers.

EXAMPLE 9

[0343] Another ceramic wiring substrate was produced. The ceramic wiringsubstrate has substantially the same configuration as in Example 8except that a ceramic wiring substrate that forms a ceramic layer isformed of such a material as Al₂O₃ sintered only at high temperature.FIGS. 17A to 17C show the production process of the multi-layeredsubstrate of this Example.

[0344] The multi-layered wiring substrate of this Example ischaracterized by including a substrate having a high strength and a highthermal conductivity, which cannot be realized by a low temperaturesintering ceramic, and a low resistance wiring of a copper foil, etc.

[0345] First, an alumina green sheet was prepared as a material for aceramic wiring substrate. This green sheet was provided with throughholes and burned before being filled with a conductive paste mentionedbelow. In the firing process, since positional data of the thoroughholes were used also in the below mentioned resin substrate (compositewiring substrate), a green sheet formed of SiC that is not sintered atthe firing temperature was laminated on both surfaces of the aluminagreen sheet. Then, the laminate was fixed by carrying out the binderremoving process and firing in the air. First, in order to remove theorganic binder in the alumina green sheet, the laminate was heated bythe use of an electric furnace in nitrogen up to 700° C. while raisingtemperatures at 25° C./hour, and treated at 1600° C. for 2 hours. Afterfiring, it was possible to remove a SiC layer easily and to obtain anAl₂O₃ substrate 1708 that has been sintered in a non-shrinkage state inthe plane direction. In this Example, a non-shrinkage process using aconstrained layer was carried out, however, a usual sintering andshrinkage process may be employed, in which equal shrinkage in threedimensions by correcting the shrinkage amount.

[0346] The via holes having a diameter of 0.15 mm that had been formedbeforehand on the Al₂O₃, substrate 1708 were filled with a thermosettingconductive paste for filling via holes 1704 by a screen printing method.The conductive paste 1704 had the same component composition asexplained in Example 8.

[0347] Furthermore, as shown in FIG. 17B, wiring substrates 1705 to 1707made of the composite sheet 1702 were laminated with the Al₂O₃ substrate1708 sandwiched therebetween. Thus, as shown in FIG. 17C, amulti-layered wiring substrate 1709 in which all layers were interlayerconnected was obtained.

[0348] Herein, the method for producing the wiring substrates 1705 to1707 using the composite sheet 1702 is described. As shown in FIG. 17A,the first transfer material 1701 (the same as in Example 8 according tothe present invention is pressed onto the uncured composite sheet 1702(the same configuration as in Example 8.

[0349] The composite sheet 1702 was provided with through holes, and thethrough holes were filled with a conductive paste 1704 that is the samepaste filled in the Al₂O₃ substrate 1708. As positional data for formingthrough holes, the same data used in forming though holes on the Al₂O₃substrate 1708 were used.

[0350] Then, similar to Example 8, by peeling off the carrier of thefirst transfer material together with the peel layer, only the wiringlayer of the first transfer material remains on the composite sheet1702. Thus, as shown in the top part of the FIG. 17B, the compositewiring substrate 1705 having a wiring layer 1703 was produced. By thesame method, composite substrates 1706 and 1707 were produced.

[0351] Thereafter, the composite wiring substrates 1705 to 1707 werelaminated on both surfaces of the Al₂O₃ substrate 1708, and subjected tothe thermal press treatment at a pressing temperature of 200° C., and ata pressure of about 2.94×10⁶ Pa (30 kgf/cm²) for 60 minutes. With thisheating and pressing treatment, an acrylic resin in the composite sheets1705 to 1707 were fused and softened. Thus, the entire wiring substratesincluding the Al₂O₃ substrate 1708 were cured and integrated into onepiece as shown in FIG. 17C. Thus, a multi-layered wiring substrate 1709was produced. The multi-layered wiring substrate has the sameconfiguration as the multi-layered wiring substrate shown in FIG. 13.

[0352] When the multi-layered wiring substrate shown in FIG. 17C andFIG. 13 were observed by the use of an X-ray, no damaged portions suchas cracks were generated in the Al₂O₃ substrate. Since the Al₂O₃substrate had a strong mechanical strength, even if the pressure was setto be about 9.8×10⁶ Pa (100 kgf/cm²), no damaged portions such as crackswere observed. Thus, it was possible to obtain a multi-layered wiringsubstrate excellent in mechanical strength such as transverse strengthetc.

[0353] In addition, when the via connection resistance of themulti-layered wiring substrate 1709 was evaluated, a copper wiringformed in a composite layer served as the low resistance wiring formedin a Al₂O₃ layer. A low resistance via connection and wiring resistancewere confirmed. The thermal conductivity of the multi-layered substrate1709 was a high thermal conductivity of about 6 W/m·K, because acomposite sheet having a high thermal conductivity was used for theresin substrate.

[0354] In this Example, the ceramic layer and the composite layer usedthe same conductive resin paste so as to form an inner via. However,different thermosetting conductive pastes may be used. Furthermore, thebase material used for the ceramic layer is not limited to Al₂O₃, andAlN having a high thermal conductivity, a low temperature burned glassceramic, and the like, may be used.

EXAMPLE 10

[0355] In the multi-layered wiring substrates in Example 8 or 9, thewiring substrate including a resin sheet on the surface portion and aceramic substrate in the middle layer. In this Example, as shown in FIG.14, a ceramic layer 1801, a resin sheet 1803, and a ceramic layer 1802were laminated in this order. In other words, the ceramic wiringsubstrate was placed on the surface portion and the wiring substrateusing a resin sheet was placed the inside layer.

[0356] In the multi-layered wiring substrate of this Example, a highdielectric layer such as a Nd₂O₅.TiO₂.SiO₂ based glass ceramic etc. isused as a ceramic layer 1801 and a low dielectric layer formed of Al₂O₃layer and borosilicate glass was used for a ceramic layer 1802. Thus,two layers each having the different dielectric constant were laminatedvia the resin sheet 1803 so as to form a dissimilar laminate.

[0357] The ceramic layer is not necessarily limited to such acombination. First, a dissimilar laminate including different kinds ofdielectric layers, for example, a magnetic material such as ferrite,etc. and a Ba—Ti—O based dielectric material is also possible.

[0358] The multi-layered wiring substrate has the following advantages.First, when the different kinds of ceramic layers are laminateddirectly, problems, for example, a mutual diffusion, warp, or the like,occur. Therefore, it may be difficult to combine ceramic layers inaccordance with the kinds of ceramic layers. However, by interposing aresin sheet between ceramic layers, it was possible to laminate thedifferent kinds of layers easily regardless of the kinds of ceramiclayers. Secondary, since the resin sheet is interposed between theceramic layers, at the time of laminating layers, no damaged portionssuch as cracks are generated in the ceramic layer.

[0359] The multi-layered wiring substrate of this Example was producedas shown in FIG. 18.

[0360] First, a Nd₂O₅.TiO₂.SiO₂ based glass ceramic green sheet 1801 anda green sheet 1802 formed of an Al₂O₃ layer and a borosilicate glass(the same, configuration as in Example 8) were prepared.

[0361] These green sheets were provided with through holes and thethrough holes were filled with a conductive paste 1803 (the same as inExample 8. Then, as shown in FIG. 18A, transfer materials 1804 and 1805having a wiring pattern were laminated while positioning from bothsurfaces. The laminate was heated and pressed at 80° C. as shown in FIG.18B, and thereafter the carrier was peeled off. Thereby, as shown inFIG. 18C, the wiring patterns of the transfer materials 1804 and 1805were transferred and formed on the green sheet 1801. Similarly, wiringpatterns were transferred to the green sheet 1802.

[0362] In this Example, as a positioning means for forming laminate, apin lamination is employed. Therefore, at predetermined positions on thegreen sheet 1801 and 1802, through holes having diameters of 3 mm Φ to3.3 mm Φ were provided. Since the green sheets 1801 and 1802 share thepositional data of the through holes with the resin substrate, they arerequired not to shrink in the firing process. Therefore, on bothsurfaces of the laminate, a green sheet formed of Al₂O₃ that is notsintered at the firing temperature was laminated, and the laminate wasfixed by carrying out the binder removing process and firing in the air.First, in order to remove the organic binder in the green sheets 1801and 1802, the laminate was heated in nitrogen by the use of an electricfurnace up to 700° C. while raising temperatures at 25° C./hour, andtreated at 900° C. for 2 hours. After firing, it was possible to removethe Al₂O₃ layer easily and to obtain a Nd₂O₅.TiO₂.SiO₂ based glassceramic substrate (1801) and an Al₂O₃ group substrate (1802), which havebeen sintered in a non-shrinkage state in the plane direction.

[0363] Next, as shown in FIG. 18D, a composite sheet 1807 filled with aconductive paste 1806 was placed between ceramic layers, that is,between the green sheets 1801 and 1802, and previously positionedthereof by the use of a pin. Thereafter, thermal press treatment wascarried out at a pressing temperature of 170° C and a pressure of7.84×10⁶ Pa (80 kgf/cm²) for 30 minutes.

[0364] Herein, when the pin for positioning had a diameter of 3 mm Φ,via holes that was not filled with paste were partially shrunk. It wasdifficult to allow the pin to penetrate through some of the via holes.However, as to the via holes in which somewhat larger via holes (3.06 mmΦ to 3.3 mm Φ)) were provided by punching by taking a shrinkage intoaccount, it was possible to allow the pin to pass through the via holeswithout any difficulties. In this case, the punching diameter may set tobe 3 mm Φ and the diameter of the pin may be made to be thinner than 3mm Φ.

[0365] Furthermore, with the heating and pressing treatment at the timeof pressing the laminate, the epoxy resin in the composite sheet 1807was fused and softened. Thus, a multi-layered wiring substrate in whichthe green sheets 1801 and 1802 that are ceramic layers were integratedwas obtained (FIG. 18E). The multi-layered wiring substrate has the sameconfiguration as the multi-layered wiring substrate shown in FIG. 14.

[0366] In the composite sheet 1807 in this Example, the wiring patternis not formed. Occasionally, a wiring pattern may be transferred in anuncured state.

[0367] Furthermore, in this Example, the composite sheet formed of aninorganic filler and an epoxy resin was used. However the compositesheet is not necessarily limited thereto, and any composite sheets, forexample, a resin sheet without containing inorganic fillers, a prepregcontaining glass fabrics, a prepreg formed of an aramide resin and aglass woven fabric, may be used.

[0368] In this Example, a sintering process that is not substantiallyshrunk in the plane direction was employed, however, a sintering processof an equal shrinkage in three dimension may be employed.

[0369] When the multi-layered wiring substrate shown in FIG. 18E wasobserved, no damaged portions such as cracks were generated in theceramic layer.

[0370] In addition, when the via connection resistance of this laminatewas evaluated, the low resistant via connection was confirmed.Furthermore, when the multi-layered wiring substrate was allowed to passthrough a reflow furnace (JEDEC level 1) at 230° C. after moistureadsorption with respect to the multi-layered wiring substrate (85° C.,85 Rh, 168 hr), as compared with the case where the via connectionresistance in which only resin substrates were laminated, the viaconnection resistance with extremely smaller resistance fluctuation wasrealized. This is an effect of the high adsorption resistance propertyof the ceramic layer.

[0371] On the other hand, as shown in for example FIG. 15, aconfiguration in which the resin base layer 1807 was laminated on bothsurfaces of the multi-layered substrate shown in FIG. 14 (or FIG. 18E)was produced as a trial product (configurations of the ceramic layer,and the resin based layer were the same as in this Example). When thedrop test with respect to the trial product was carried out, as comparedwith the configuration using only the ceramic wiring substrate, it wasconfirmed that extremely little damage such as cracks was generated.

[0372] The base material to be used in the resin layer 1807 that is anoutermost layer is not necessarily a composite sheet used in the middlelayer. It can be selected for in accordance with the applications ofuse, and for example, a glass epoxy resin, etc. can be used.

[0373] The above-mentioned results show that the substrate having bothan advantage of a ceramic and an advantage of a resin can be realized.

[0374] As mentioned above, the present invention can provide a transfermaterial capable of transferring a fine wiring pattern at a lowtemperature without distortion of pattern, reliably and easily. And byusing the transfer material, it is possible to realize a wiringsubstrate having a fine wiring pattern and advantageous in flip-chipmounting of the semiconductor device, etc.

[0375] Furthermore, since the transfer material has a wiring layerformed in a convex shape, an IVH can be compressed easily. Thus, it isadvantageous in stabilizing the via connection.

[0376] Furthermore, since the transfer material of the present inventiontransfers only the wiring pattern (second metal layer etc.), so that thematerials for forming the first metal layer that is a carrier can bereused, thus realizing a low cost. Furthermore, it is useful from theviewpoint of industrial applicability.

[0377] Furthermore, the wiring substrate of the present invention has aconfiguration in which a wiring pattern is not projected from thesubstrate. Thus, the multi-layered wiring substrate in which a ceramicwiring substrate and a resin base wiring substrate are laminated, whichhas been difficult to form due to the damage for the ceramic layer atthe lamination, easily can be produced.

[0378] Moreover, in each of the transfer materials of Examples 1 to 10,it is also possible to form circuit components such as an inductor, acapacitor, a resistor, a semiconductor device, or the like, forelectrically connecting to the wiring pattern, and to transfer them tothe substrate together with the wiring pattern. It is preferable thatthe passive components such as inductor, capacitor, and resistor, etc.are formed on the substrate by a printing method, for example a screenprinting method.

[0379] Fifth Embodiment

[0380] In the above-mentioned embodiments, the transfer materials fortransferring the wiring pattern to the substrate (first to thirdtransfer materials) are explained. The following embodiments describeanother transfer materials according to the present invention, that is,a component and wiring pattern transfer and formation material fortransferring a wiring pattern and a circuit component to the substratesimultaneously.

[0381]FIGS. 19A and 19B are cross-sectional views showing a schematicconfiguration of a component and wiring pattern transfer and formationmaterial (hereinafter, fourth transfer material will be referred to)according to one embodiment of the present invention.

[0382] As shown in FIG. 19A, in a fourth transfer material 2001A, on awiring pattern transfer and formation material having a two-layeredstructure in which a wiring metal foil 2102 that is a second metal layeris formed on a mold release carrier metal foil 2101 that is a firstmetal layer, circuit components (an inductor 2103, a capacitor 2104 anda resistor 2105) are formed for electrically connecting to the wiringmetal foil 2102 by a printing method.

[0383] Furthermore, as shown in FIG. 19B, numeral 2001B denotes anotherembodiment of the fourth transfer material. The transfer material 2001Bhas substantially the same configuration as the transfer material 2001Ashown in FIG. 19A. However, in this embodiment, not only a passivecomponent such as the inductor 2103, the capacitor 2104, the resistor2105, etc., but also a positive component such as a semiconductor chip2106, etc. is flip-chip mounted on a connection portion 2107 so that thecomponents are adhered to the wiring metal foil 2102.

[0384] Each of the transfer materials shown in FIGS. 19A and 19B ispressed onto the substrate and only the mold release carrier 2101 ispeeled off. Thus, components excluding the mold release carrier 2101,that is, the metal foil for wiring 2102, the inductor 2103, thecapacitor 2104, and the resistor 2105, etc., and a positive componentsuch as the semiconductor chip 2106, etc. can be transferred to thesubstrate.

[0385] Sixth Embodiment

[0386] Next, FIG. 20 shows a schematic configuration of a component andwiring pattern transfer and formation material (hereinafter, a fifthtransfer material will be referred to) according to a sixth embodimentof the present invention.

[0387] As shown in FIG. 20, in a fifth transfer material 2002, on awiring pattern transfer and formation material having a three-layeredstructure in which a mold release carrier metal foil 2201 that is afirst metal layer, a peel layer 2202 formed on the first metal layer,and a wiring metal foil 2203 that is a second metal layer formed on thepeel layer 2202, an inductor 2204, a capacitor 2205 and a resistor 2206are formed for electrically connecting the wiring metal foil 2203 by aprinting method.

[0388] Seventh Embodiment

[0389] Next, FIG. 21 shows a schematic configuration of a component andwiring pattern transfer and formation material (hereinafter, a sixthtransfer material will be referred to) according to a further embodimentof the present invention.

[0390] As shown in FIG. 21, in a sixth transfer material 2003, on awiring pattern transfer and formation material having a three-layeredstructure in which a mold release carrier metal foil 2301 that is afirst metal layer, a peel layer 2302, and a wiring metal foil 2303 thatis a second metal layer, an inductor 2304, a capacitor 2305 and aresistor 2306 are formed for electrically connecting to the wiring metalfoil 2303 by a printing method.

[0391] The mold release carrier metal foil 2301 has a concave and convexportion on the surface portion thereof The convex portion corresponds toa wiring pattern. On the region of the convex portions, a peel layer2302 made of an organic layer or a metal plating layer and a metal foilfor wiring 2303 are formed. The mold release carrier metal foil 2301 isadhered to the metal foil for wiring 2303 via the peel layer 2302.

[0392] It is preferable in the fourth to sixth transfer materials thatthe adhesive strength between the first metal layer and the second metallayer via the peel layer is weak, for example, 50 N/m (gf/cm) or less.In the fourth transfer material, by plating or an evaporation method,two metal layers are not peeled off from each other in the processes ofetching, plating, washing in water, and the like. However, it is shownthat only the second metal layer can be peeled off easily in a peelingprocess. Furthermore, a passive component pattern formed by a printingmethod can be peeled off easily from the first metal layer that is acarrier.

[0393] On the other hand, in the fifth and sixth transfer materials, athin organic layer having an adhesive strength and a thickness of lessthan 1 μm is used for the peel layer. As the material for the organiclayer, for example, an urethane resin, an epoxy resin, a phenol resin,and the like, which are thermosetting resins, can be used. However, thematerial is not necessarily limited thereto, and other thermoplasticresin, etc. can be used. However, if the thickness is 1 μm or more, thepeeling property of the peel layer is deteriorated, which may make thetransfer difficult.

[0394] On the other hand, in order to lower the adhesive strengthintentionally, a plating layer may be interposed as the peel layer. Forexample, a nickel plating layer, a nickel-phosphorous alloy layer, analuminum plating layer, or the like, having a thickness of less than 1μm, can be used as the peel layer so as to provide the transfer materialwith a peeling property.

[0395] Thus, in the wiring portion including a second metal layer, atthe time of transfer, the second metal layer can be peeled off from thefirst metal layer easily, and the second metal layer and componentpattern can be transferred to the substrate easily. A suitable thicknessof the peel layer formed of the metal layer is about 100 nm to 1 μm.Since the process cost is increased with the increase in thickness, thethickness is desirably less than 1 μm.

[0396] Moreover, in the fifth and sixth transfer materials, the secondmetal layer and the passive component pattern formed by a printingmethod can be peeled off easily from the first metal layer that is acarrier.

[0397] Furthermore, it is preferable in the fourth to sixth transfermaterials that the first metal layer includes at least one metalselected from the group consisting of copper, aluminum, silver andnickel, and particularly copper. Furthermore, it is preferable that thesecond metal layer, similar to the first metal layer, includes at leastone metal selected from the group consisting of copper, aluminum, silverand nickel. It is preferable that the fourth transfer material includessilver, and the firth and sixth transfer materials include copper.Copper is used for the first metal layer because of its low cost.Namely, copper foils having various kinds of predetermined thickness arecommercially available. Copper is used for the second layer because ofits easiness in plating.

[0398] Furthermore, in the sixth transfer material, there is an effectof controlling a process with one etching liquid if the first metallayer and the second metal layer are formed of the same metal. Inparticular, when the metal layers are formed of copper, it isadvantageous in that the conditions for carrying out the etching processhave been investigated in detail. Moreover, one kind of metal may beused, and the combination of two metals or more may be used.

[0399] Furthermore, it is preferable in, for example, an etching processetc. of the sixth transfer material that when the peel layer and thesurface portion of the first metal layer are removed by etching process(see FIG. 21), the first metal layer and the second metal layer includethe same metal component. Moreover, in a case where the plating layer isused for a peel layer, the configuration shown in FIG. 21 can beprocessed with a copper etching liquid, but the configuration shown inFIG. 20 cannot be processed with a copper etching liquid. Furthermore,in the case where the first metal layer and the second metal layerinclude the same metal components, the kinds of the metal are notparticularly limited. However, it is formed of a copper foil preferably,and particularly preferably an electrolytic copper foil because of itsexcellent conductivity. Moreover, one kind of metal may be used, and thecombination of two metals or more may be used.

[0400] In the fourth to sixth transfer materials, the thickness of thefirst metal layer is preferably 1 to 18 μm, and more preferably 3 to 12μm. When the thickness is less than 3 μm, when the second metal layer istransferred to the substrate, an excellent electric conductivity may notbe exhibited. On the contrary, when the thickness is 18 μm or more, itmay be difficult to form a fine wiring pattern.

[0401] In the fourth and fifth transfer materials, the thickness of thefirst metal layer is preferably 4 to 10 μm, and more preferably 20 to 70μm. The first metal layer serves as a carrier, and occasionally, asshown in FIG. 21, the surface portion thereof as well as the wiringpattern is etched so as to form a convex and concave portion. Therefore,the first metal layer is desired to be a metal layer having a sufficientthickness. Furthermore, since the fourth to fifth transfer materialshave a carrier layer that is a metal layer (first metal layer), theyexhibit sufficient mechanical strength or thermal resistance withrespect to the thermal distortion or stress distortion in the directionof the plane, which are generated at the time of transfer.

[0402] The material for forming passive components electricallyconnected to the wiring pattern is a paste material. It is preferablethat when the substrate to which the passive components are transferredis made of, for example, a thermosetting resin, a material for thepassive components also contains the thermosetting resin. When theinductor is formed, a magnetic metal powder or ferrite is used as thefiller to be mixed in the thermosetting resin. When the capacitor isformed, a high dielectric ceramic powder, for example, barium titanate,Pb based perovskite, or the like, is used similarly as the filler. Whenvarious kinds of resistors are formed, carbon, etc. is used as thefiller. In this case, by varying the content of carbon, the resistancevalue can be adjusted. When the resistor is formed in a thin film,Nichrome alloy, chromium silicon, tantalum nitride, ITO, or the like, isused.

[0403] On the other hand, with the fourth or fifth transfer material, apattern transfer can be formed at low temperature of 100° C. or less, sothat it is possible to form a component wiring pattern on the ceramicgreen sheet.

[0404] On the other hand, when the substrate to which the passivecomponents are transferred is a ceramic, a material (paste) to be usedfor printing the passive component is preferably a material in whichonly filler is remained through the binder removing process. Therefore,a vehicle in which a binder having an excellent thermal deformationproperty is dissolved, for example, paste vehicle in which a binder isdissolved in terpineol, is used. Specifically, the paste materialcapable of screen printing is formed by kneading various fillerscorresponding to the property of the inductor, the capacitor, and theresistor, respectively, by the use of a triple roller.

[0405] When the inductor is formed, a material obtained by mixing amagnetic metal powder, or a ferrite that is sintered at low temperatureas the filler with a glass is used as the filler. When the capacitor isformed, barium titanate, glass, and Pb based perovskite, and the like,is used as the filler similarly. When the resistor is formed, a materialobtained by mixing a ruthenium pyrochlore, ruthenium oxide, lanthanumborite, as a filler, with glass is used. These materials can be sinteredtogether with the substrate, ceramic that is sintered at a lowtemperature. Furthermore,even in the case of the inner layer resistor,it is possible to adjust the resistant value relatively easily.

[0406] Eighth Embodiment

[0407] One example of a method for producing the fourth transfermaterial (see FIGS. 19A and 19B) is described in this embodiment.

[0408] This production method includes the following steps (1) and (2);

[0409] (1) forming a two-layered structure in which a second metal layer2403 that is a wiring pattern is directly adhered to the first metallayer 2401 that is a carrier (see FIGS. 22A to 22E); and

[0410] (2) forming component patterns 2405, 2406, 2407 and 2408 by aprinting method with positioning so that they are electrically connectedto the second metal layer 2403 (see FIGS. 22E and 22E′).

[0411] In the steps shown in FIGS. 22A to 22E′, a pattern opposite tothe wiring pattern is formed on the first metal layer 2401 by using adry film resist 2404 and then, the wiring pattern formed of a metal foil(second meat layer 2403) is formed by a direct drawing method, forexample, pattern plating or a sputtering method, an evaporation method,and the like. Thus, it is possible to form a fine wiring pattern.

[0412] Furthermore, when it is produced by plating, a metal foil forminga second metal layer 2402 may be the same as the metal foil (forexample, a copper foil) forming the first metal layer 2401 or may beformed of a silver plating film that is a different metal. Furthermore,the metal foil of the first metal layer can be reused. Therefore, lowcost can be realized and the industrial applicability is excellent.

[0413] A suitable method for forming passive components for electricallyconnecting the wiring pattern is a printing method. As the printingmethod, any of an off set printing, a gravure printing, a screenprinting, etc, may be employed, however, the screen printing method ispreferred. In the pattern used for the resistor, the suitable thicknesssometimes is 1 μm or less. In such a case, a dielectric layer producedby a PVD method or a CVD method can be attached.

[0414] The line width of the wiring pattern is usually required to be asthin as about 25 μm. In the present invention, such a line width ispreferred.

[0415] Ninth Embodiment

[0416]FIGS. 23A to 23F show one example of a method for producing thefifth transfer material (see FIG. 20).

[0417] This production method includes the following steps (1) to (3);

[0418] (1) forming a three-layered laminate in which a first metal layer2501, a peel layer 2502 made of an organic layer or a metal platinglayer and the second metal layer 2503 containing the same metalcomponent as that contained in the first metal layer 2501 are laminated(see FIG. 23A);

[0419] (2) forming a wiring pattern for transfer 2503 a (see FIG. 23E)by processing the second metal layer 2503 into a wiring pattern, with anentire peel layer maintained, by a chemical etching process (see FIGS.23B to 23E); and

[0420] (3) forming component patterns (an inductor 2505, a capacitor2506 and a resistor 2507) by a printing method with positioning so thatthey are electrically connected to the layer 2503 (see FIG. 23F);

[0421] In the process for forming the wiring pattern described in (2),in the step shown in FIG. 23B, a dry film resist 2504 is adhered to thesecond metal layer 2503. In the step shown in FIG. 23C, the wiringpattern region is formed by exposing the pattern. In the step shown inFIG. 23D, the dry film resist is removed from a region (2504 b)excluding the wiring pattern 2504 a by developing and etching. In thestep shown in FIG. 23E, the remained dry film resist is removed.

[0422] Specifically, the chemical etching process is carried out asfollows. When the aqueous solution of basic cupric chloride including anammonium ion is used as an etchant, when the peel layer 2502 is formedof, for example, a nickel-phosphorous alloy layer, only the second metallayer 2503 can be etched. Thereafter, by using, as an etching liquid, amixed liquid including nitrate and hydrogen peroxide solution, only thepeel layer 2502 can be removed. With this method, the wiring portiontransferred to the substrate does not become a concave portion. Thus,the surface of the substrate can be made flat.

[0423] Tenth Embodiment

[0424] Next, FIGS. 24A to 24F show one example of a method for producingthe sixth transfer material (see FIG. 21).

[0425] The steps of FIGS. 24A to 24F are the same as in the method forproducing the fifth transfer material of the ninth embodiment except thefollowing steps.

[0426] In other words, in the method for producing the fifth transfermaterial, only the second metal layer and the peeling layer areprocessed into the pattern by a chemical etching process, however, inthe method for producing the sixth transfer material, the surfaceportion of the first metal layer 2601 also is processed into the wiringpattern by the chemical etching process as shown in FIGS. 24D and 24E.Namely, a convex and concave portion is formed on the surface portion ofthe first metal layer 2601. As shown in FIG. 24F, component patterns (aninductor 2605, a capacitor 2606, and a resistor 2607) are formed byprinting with positioning so that the components are electricallyconnected to the wiring pattern.

[0427] According to the method for producing the fourth to sixthtransfer materials, it is possible to form a fine wiring pattern becausethe metal layer of the wiring pattern is formed by a chemical etchingprocess such as photolithography, etc. Furthermore, in the case of themethod for producing the sixth transfer material, by making the metalfoil of the wiring pattern (second metal layer) to be the same as thatcontained in the metal foil of a carrier (first metal layer), it ispossible to make the surface portion of the carrier to have the sameconvex and concave portion as that of the wiring pattern in one etchingprocess.

[0428] As mentioned above, it is possible to reuse the componentmaterials except the second metal layer. Furthermore, in the sixthtransfer material, since the first metal layer is processed in a wiringpattern, it is possible to reuse the first metal layer in a differentpattern formation as letterpress printing. Therefore, a low cost andexcellent industrial applicability can be realized.

[0429] Moreover, in the method for producing the fourth to sixthtransfer materials, the second metal layer is formed by electrolyticplating. Furthermore, a further metal layer (third metal layer) may beformed by electrolytic plating on the second metal layer. When the thirdmetal layer or second metal layer for forming wiring pattern is formedby electrolytic plating, appropriate adhesive strength can be obtainedbetween the second metal layer and the third metal layer. Moreover, agap between the metal layers occurs, so that an excellent wiring patterncan be formed. Or, the pattern can be formed by masking the wiringpattern after the third metal layer is formed on the second metal layerby panel plating. In this case, an effect of preventing the surface ofthe transferred second metal layer from being oxidized and improving thewettability of the soldering can be obtained.

[0430] Moreover, it is preferable in the method for producing the wiringpattern for transfer that before the third metal layer is formed on thesecond metal layer, the surface of the second metal layer is roughened.The term “before the third metal layer is formed” means before a maskfor forming the wiring pattern is formed on the second metal layer, orbefore the third metal layer is formed along the wiring pattern on thesecond metal layer on which masking is performed in the wiring patternThus, the second metal layer is roughened, the adhesion between thesecond metal layer and the third metal layer is improved.

[0431] Furthermore, it is preferable in the method for producing thetransfer material that the fourth metal layer that is different from thefirst to third metal layers can be formed by electrolytic plating. It ispreferable that by selecting a component that is chemically stable withrespect to the etching liquid corroding the first to third metal layersas the material for the fourth metal layer, the second, third, andfourth metal layers can be processed into the wiring pattern along withthe surface layer portion of the first metal layer without reducing thethickness of the second, third, and fourth metal layers.

[0432] For the fourth metal layer, for example, Ag, Au, or the like,having chemical stability and the low resistance property are desirable.Since these metals are not likely to be oxidized, the adhesion betweenthe plating wiring layer plated with these metals and for example, a viahole that is preliminarily formed on the substrate, a bump of a barechip, or conductive adhesive can be further stabilized.

[0433] In the method for producing the fifth and sixth transfermaterials, as a method for forming passive components for electricallyconnecting the wiring pattern, a printing method is suitable same as inthe fourth transfer material. When the peel layer is formed of a platinglayer such as a nickel plating layer or a nickel-phosphorous alloylayer, as the printing method, any of an off set printing, a gravureprinting, screen printing, etc may be employed, and the screen printingis preferred.

[0434] Furthermore, the materials used for printing of the componentpattern are preferred to be paste. As in the fourth transfer material,when the substrate-on which the passive components are transferred ismade of, for example, a thermosetting resin, a material for the passivecomponents also contains the thermosetting resin. When the inductor isformed, as the filler to be mixed with the thermosetting resin, amagnetic metal powder or ferrite can be used. When the capacitor isformed, as the filler similarly, high dielectric ceramic powder, forexample, barium titanate, Pb based perovskite, or the like, can be used.When the resistor is formed, as the filler, carbon is used. As to theresistance value, by varying the content of carbon, the resistance valuecan be controlled. When the resistor is formed in a form of a thin film.The material for a resistor and the production method are the same as inthe fourth transfer material.

[0435] Since in the fifth transfer material, like a fourth transfermaterial, a pattern transfer can be formed at low temperature of 100° C.or less, so that it is possible to form a component wiring pattern onthe ceramic green sheet.

[0436] When the substrate on which the components are transferred is aceramic substrate, a material (paste) to be used for printing thecomponent pattern is preferably a material in which only the fillerremains after a binder removing process. Therefore, a vehicle in which abinder having an excellent thermal deformation property is dissolved,for example, paste vehicle in which a binder is dissolved in terpineolis used. Specifically, the paste material capable of screen printing isformed by kneading various fillers corresponding to the property of theinductor, capacitor, and resistor, respectively, by using a tripleroller.

[0437] When the inductor is formed, a material obtained by mixing aglass and filler is used. As the filler, a magnetic metal powder and aferrite that is sintered at low temperature with are used. When thecapacitor is formed, as the filler similarly, barium titanate, Pb basedperovskite, or the like is used. When the resistor is formed, as thefiller, a material obtained by mixing a ruthenium pyrochlore, rutheniumoxide, lanthanum borite with a glass is used. These materials can besintered together with the ceramic substrate that is sintered at a lowtemperature. Furthermore, even in the case of an inner layer resistor,it is possible to adjust the resistance value relatively easily.

[0438] These two kinds of fifth and sixth component and wiring patternformation and transfer materials can be used in different waysappropriately. For example, when the component wiring pattern formed inthe transfer material is transferred to the inside layer of the laminatesubstrate, in particular, when the via is formed directly on the via, itis preferable that the transfer material shown in FIG. 20 (fifthtransfer material) is preferably used, from the viewpoint of the viaconnection.

[0439] On the other hand, when transferred to the surface portion, inparticular, when the distance between terminals of the inductor,capacitor, semiconductor chip is small, the transfer material (sixthtransfer material) that is partially processed to the carrier layershown in FIG. 21 is preferred form the purpose of reducing the creepingdistance.

[0440] Eleventh Embodiment

[0441] Next, FIGS. 22G, 22G′, 23H, and 24H show one embodiment of thecircuit component produced by the use of the fourth to sixth transfermaterials.

[0442] A circuit substrate using the fourth to sixth transfer materialscan be produced by at least two methods. The first method for producingthis embodiment includes the following steps:

[0443] A step in which the transfer materials of the fifth to seventhembodiment are prepared (see FIGS. 22E, 23F, and 24F). This transfermaterial is placed so that the side on which the component wiringpatterns are formed is brought into contact with a least one surface ofthe substrate so as to adhere thereto.

[0444] A step in which by peeling off first metal layer that is acarrier from the transfer material adhered to the base material sheet,the component wiring pattern including at least the second metal layerand the component pattern is transferred to the base material sheet.Thus, a substrate in which components are incorporated is produced (seeFIGS. 22G, 23H, and 24H).

[0445] Thus, the fine wiring pattern and the component pattern includingan inductor, a capacitor, and a resistor, and a semiconductor chip isformed on the base material sheet in flat form (see FIGS. 22G and 23H)or in a form of a concave shape (see FIG. 24H). Furthermore, in the thusproduced wiring substrate, when for example the wiring portion is in aconcave shape (FIG. 24H), the positioning of the wiring portion and thebump of the semiconductor chip can be carried out easily and theexcellent flip-chip mounting of the semiconductor is provided.

[0446] Twelfth Embodiment

[0447] Furthermore, the second method for producing the circuitsubstrate of the present invention is a method for producing amulti-layered circuit substrate shown in FIG. 25. In this productionmethod, the substrate circuits (see FIGS. 22G, 23H, 24H, and the like)obtained in the eleventh embodiment are laminated in two layers or more.

[0448] Herein, numeral 2702 and 2709 denote a second metal layer forminga wiring pattern, 2703 denotes a resistor, 2704 denotes a capacitor,2705 denotes an inductor, and 2706 denotes a base material sheet.

[0449] Since with this circuit substrate, a component pattern and awiring pattern can be transferred and formed at low temperature of 100°C. or less, it is possible to maintain an uncured state not only in theceramic green sheet but also in the sheet using a thermosetting resin.Thus, the circuit substrate is laminated in two layers or more in anuncured state and then the laminate is heated and cured in oneoperation.

[0450] Therefore, in the multi-layered circuit substrate of four layersor more, it is not necessary to correct the curing and shrinkage foreach layer. Thus, it is possible to form a multi-layered circuitsubstrate having a fine wiring pattern and a component pattern can beproduced. However, the shape of the wiring portion and the componentportion forming an inner layer is not necessarily concave but may beflat. Therefore, the circuit substrate etc. as shown in FIGS. 22G and23H can be used.

[0451] It is preferable in the production method described in theeleventh embodiment and this embodiment that the base material sheetincludes an inorganic filler and a thermosetting resin, is provided withat least one through hole and the through hole is filled with aconductive paste. Thus, it is possible to obtain a composite wiringsubstrate for high-density mounting, which has an excellent thermalconductivity and has an IVH structure in which the wiring pattern iselectrically connected to the conductive paste easily.

[0452] Furthermore, when the base material sheet is used, when thewiring substrate is formed, high temperature treatment is not required.This can be performed sufficiently at about 200° C., i.e., the curingtemperature of the thermosetting resin.

[0453] The base material sheet preferably contains 70 to 95 weight % ofan inorganic filler and 5 to 30 weight % of a thermosetting resin, andmore preferably contains 85 to 90 weight % of an inorganic filler and 10to 15 weight % of a thermosetting resin. Since the base material sheetcan contain inorganic fillers with a high concentration, by changing thecontent of inorganic fillers, the coefficient of thermal expansion,thermal conductivity, dielectric constant, and the like, can be setarbitrarily.

[0454] It is preferable that the inorganic filler includes at least oneinorganic filler selected from the group consisting of Al₂O₃, MgO, BN,AlN and SiO₂. By determining the kinds of inorganic filler properly, itis possible to set, for example, the coefficient of thermal expansion,thermal conductivity, and dielectric constant to the desirableconditions. For example, it is possible to set the coefficient ofthermal expansion of the base material sheet in the plane direction tobe substantially the same as the coefficient of thermal expansion of asemiconductor to be mounted, and to provide a high thermal conductivity.

[0455] The base material sheet using, for example, Al₂O₃, BN, AlN andthe like, among the inorganic fillers, is excellent in thermalconductivity. The base material sheet using MgO is excellent in thermalconductivity and capable of raising the constant of thermal expansion.Furthermore, when SiO₂, particularly amorphous SiO₂ is used, a basematerial sheet having a small constant thermal expansion, a light weightand low dielectric constant can be obtained. Moreover, the inorganicfiller can be used singly or by combination of two kinds or more of theinorganic fillers.

[0456] The base material sheet including the inorganic filler and thethermosetting resin composition can be produced by, for example, thefollowing method. First, a solution for adjusting the viscosity is addedinto a mixture including the inorganic filler and the thermosettingresin composition so as to prepare slurry having an arbitrary slurryviscosity. An example of the solvent for adjusting the viscosityincludes, for example, methyl ethyl ketone, toluene, and the like.

[0457] Then, the slurry is formed into a film on the preliminarilyprepared mold release film by a doctor blade method, etc. and the filmis treated at a temperature below the curing temperature of thethermosetting resin so as to volatilize the solvent for adjusting theviscosity. Thereafter, the mold release film is removed, therebyproducing a base material sheet.

[0458] The thickness of the film at the formation is appropriatelydetermined by the amount of the solvent for adjusting viscosity to beadded. Usually the thickness ranges from 80 to 200 μm. Furthermore, theconditions for volatilizing the solvent for adjusting viscosity isappropriately determined in accordance with the kinds of solvents foradjusting viscosity, kinds of thermosetting resins, or the like.However, usually, the volatilization is carried out at a temperature of70 to 150° C. for 5 to 15 minutes.

[0459] As the mold release film, usually, an organic film can be used.For example, it is preferable to use an organic film containing at leastone resin selected from the group consisting of, for example,polyethylene, polyethylene terephthalate, polyethylene naphthalate,polyphenylene sulfide (PPS), polyphenylene terephthalate, polyimide andpolyamide, and more preferably PPS.

[0460] Furthermore, another example of the base material sheet includesa sheet reinforcer impregnated with a thermosetting resin composition,and having at least one through hole filled with a conductive paste.

[0461] The sheet reinforcer is not particularly limited as long as it isa porous material capable of holding the thermosetting resin. However,it is preferable that the sheet reinforcer is at least one selected fromthe group consisting of a glass fiber woven fabric, a glass fibernon-woven fabric, a woven fabric of a thermal resistant organic fiberand a non-woven fabric of a thermal resistant organic fiber. An exampleof the thermal resistant organic fiber includes, for example, allaromatic polyamide (aramide resin), all aromatic polyester, polybutyleneoxide, and the like. In particular, aramide resin is preferable.

[0462] The thermosetting resin is not particularly limited as long as ithas a thermal resistance property. However, because of its excellentthermal conductivity, a resin containing at least one selected from thegroup consisting of an epoxy resin, a phenol resin, a cyanate resin anda polyphenylene phthalate resin. Furthermore, the thermosetting resincan be used singly or by combination of two kinds or more of thethermosetting resins.

[0463] Such a base material sheet can be produced, for example, byimmersing the reinforcer sheet into the thermosetting resin composition,and then drying to half-cured state.

[0464] It is preferable that the immersion is carried out so that therate of the thermosetting resin with respect to the base material sheetis 30 to 60 weight %.

[0465] It is preferable in the production method that when the basematerial sheet containing a thermosetting resin is used, the wiringsubstrates are laminated by a heating and pressing treatment so as tocure the thermosetting resin. This can be performed sufficiently atabout 200° C., i.e., the curing temperature of the thermosetting resin.

[0466] The reinforcer sheet may be a film such as polyimide, LCP,aramide etc. coated with the thermosetting resin.

[0467] On the other hand, the wiring substrate is not necessarilylimited to the resin substrate, and it may be a ceramic substrate. Inthis case, a green sheet containing an organic binder, plasticizer, andceramic powder and having at least one through hole filled with theconductive paste can be used as a base material sheet. This basematerial sheet has a high thermal resistance, an excellent sealingproperty and excellent thermal conductivity.

[0468] The ceramic powder preferably contains at least one ceramicselected from the group consisting of Al₂O₃, MgO, Zro₂, TiO₂, BeO, BN,SiO₂, CaO and glass. More preferably, the ceramic powder is a mixture of50 to 55 weight % of Al₂O₃ and 45 to 50 weight % of glass powder.Moreover, the ceramic can be used singly or in combination of two kindsor more of them.

[0469] An example of the binders to be used includes, for example,polyvinyl butyrate (PVB), acrylic resin, methyl cellulose resin, and thelike. An example of the plasticizer includes, for example, butyl benzylphthalate (BBP), dibutylphthalate (DBP), and the like.

[0470] Such a green sheet containing a ceramic can be produced by, forexample, the same method as that for producing the base material sheetincluding the inorganic filler and the thermosetting resin. Moreover,the treating conditions are appropriately determined by the kinds of thecomponent materials, etc.

[0471] For example, when the second metal layer 2403 of the transfermaterial shown in FIG. 22, which is a wiring layer, is formed of silver,since silver has an oxidation resistant property, a binder removingprocess and firing in the air are possible. Thus, the production processbecomes easy. On the other hand, when the second metal layer 2503 and2603 of the transfer materials shown in FIGS. 23 and 24 are formed ofcopper, the wiring portion to be transferred is a base metal that islikely to be oxidized easily, the binder removing process in anon-oxidization atmosphere, for example in an nitrogen atmosphere, ornitrogen firing process is required. Therefore, the green sheet isrequired to have a configuration corresponding to the nitrogen process.Furthermore, also vehicle and binder used for printing of the inductor,capacitor, and resistor, are strongly required to have a thermaldeposition property under the non-oxidation atmosphere.

[0472] The thickness of the base material sheet is usually 100 to 250μm.

[0473] It is preferable that the base material sheet has at least onethrough hole and the through hole is filled with a conductive paste. Theposition of the through hole is not particularly limited as long as thethrough hole is formed so that it is in contact with the wiring pattern.However, it is preferable that through holes are positioned at equalintervals of 250 to 500 μm pitch.

[0474] The size of the through hole is not particularly limited, butusually, the diameter is 100 to 200 μm, and more preferably 100 to 150μm.

[0475] The method for forming through holes is appropriately determinedin accordance with the kinds of the base material sheet, etc. However,the preferable example of the method includes, for example, a carbondioxide gas laser process, a process with a punching machine, a bulkprocess with a mold, and the like.

[0476] The conductive paste is not particularly limited as long it hasconductivity. However, usually, a resin containing a particulateconductive metal, and the like, can be used. An example of theconductive metal material to be used includes, for example, copper,silver, gold, silver-palladium, and the like. An example of thethermosetting resin includes an organic binder of, for example, an epoxyresin, a phenol resin, a cellulose resin, an acrylic resin, and thelike.

[0477] The amount of the conductive metal material in the conductivepaste is usually 80 to 95 weight %. Furthermore, when the base materialsheet is a green sheet, thermal plasticizer binder is used instead ofthermosetting, and glass powder is used as an adhesive agent.

[0478] Next, the method for adhering the transfer material to the basematerial sheet and the method for peeling off the first metal layer fromthe second metal layer are not particularly limited. However, when thebase material sheet includes a thermosetting resin, for example, theadhering method and the peeling method can be carried out as follows.

[0479] First, the transfer material (FIG. 23F) and the base materialsheet 2508 are placed as shown in FIG. 23G, and heated and pressed so asto fuse and soften the thermosetting resin in the base material sheet,thus allowing the metal layer 2503 having a wiring patterns and passivecomponent patterns 2505, 2506, and 2507 to be embedded in the basematerial sheet. Herein, numeral 2505 denotes an inductor, 2506 denotes acapacitor, and 2507 denotes a resistor. However, it is preferable thatwhen a circuit component such as a capacitor that needs to haveelectrodes on both surfaces of the dielectric layer is transferred, onlythe wiring pattern 2510 corresponding to the wiring pattern ispreliminarily formed on the base material sheet 2508 preliminarily (seeFIG. 23G,).

[0480] Then, the base material sheet on which the transfer material ispressed is treated at a softening temperature or a curing temperature ofthe thermosetting resin. In the latter case, the resin is cured, whichallows the adhesion between the transfer material and the base materialsheet and the adhesion between the second metal layer 2503 and the basematerial sheet 2508 to be fixed.

[0481] The conditions for heating and pressing treatment are notparticularly limited as long as the thermosetting resin is not perfectlycured. However, the heating and pressing usually can be carried outunder the pressure of 9.8×10⁵ to 9.8×10⁶ Pa (10 to 100 kgf/cm²), at thetemperature of 70 to 260° C. for 30 to 120 minutes.

[0482] Then, after the transfer material (FIG. 23F) and the sheetsubstrate 2508 are adhered to each other, for example, the first metallayer 2501 that is the carrier layer is pulled so as to peel it off withthe peeling layer. Thus, the first metal layer 2501 can be peeled offfrom the second metal layer 2503 and the passive component 2505, 2506and the 2507.

[0483] Namely, since the adhesive strength between the first metal layerand the second metal layer via the peeling layer is weaker than theadhesive strength between the base material sheet and the second metallayer that is a wiring layer, the adhering surface between the firstmetal layer and the second metal layer is peeled off, and only thesecond metal layer is transferred to the base material sheet while thefirst metal layer is peeled off (see FIG. 23H).

[0484] Curing of the thermosetting resin may be carried out after thefirst metal layer is peeled off from the component wiring pattern.

[0485] On the other hand, when the base material sheet is a green sheetforming the ceramic substrate, the following method can be employed. Forexample, in FIGS. 22A to 22D, a copper foil is used for the first metallayer, and silver wiring is formed for the second metal layer 2403 thatis a wiring layer. Thereafter, a passive component etc. is formed by ascreen printing method for electrically connecting the silver wiring,thus forming a component for transfer and a wiring pattern. However,since in the case of the ceramic substrate, firing also is carried out,the semiconductor chip as shown in FIG. 22E′ is not mounted. By carryingout the same heating and pressing treatment as mentioned above, thecomponent wiring pattern is allowed to be embedded in the green sheetthat is a base material sheet and to adhere the green sheet and thecomponent wiring pattern for transfer.

[0486] Thereafter, as mentioned above, by peeling the carrier, thecomponent material other than the component wiring pattern is removed.Then, on the green sheet on which the component wiring pattern istransferred, an alumina green sheet for constraint is laminated.Thereafter, the binder removing process and the sintering treatment arecarried out in the air, thus to sinter the ceramic and to fix thetransferred second metal layer and the component pattern onto theceramic substrate. Since the transfer material has a wiring pattern madeof silver, it is advantageous that the binder removing process and thefiring can be carried out in the air.

[0487] On the other hand, in the case of the methods shown in FIGS. 23Ato 23H, and the FIGS. 24A to 24H, the first metal layer is formed of acopper foil, and a copper wiring is formed as the second metal layer,that is, a wiring layer is formed by a chemical etching process usingthe photolithography. The copper wiring can be produced more cheaplythan the silver wiring produced by plating, and is excellent inmigration resistance property. Thereafter, a passive component etc. isformed by a screen printing method for electrically connecting to thecopper wiring. Thus, the component wiring pattern for transfer isproduced.

[0488] However, since in the case of the ceramic substrate, firing alsois carried out, the semiconductor chip as shown in FIG. 22E′ is notmounted. By carrying out the same heating and pressing treatment asmentioned above, the component wiring pattern is allowed to be embeddedin the green sheet that is a base material sheet and to adhere the greensheet and the component wiring pattern for transfer.

[0489] Thereafter, as mentioned above, by peeling the carrier, thecomponent material other than the component wiring pattern is removed.

[0490] Then, on the green sheet to which the component wiring pattern istransferred, an alumina green sheet for constraint is laminated.Thereafter, in such an atmosphere in which copper is not oxidized, forexample, nitrogen atmosphere, a binder removing process and firing arecarried out, thereby sintering the ceramic. Thereby, the transferredsecond metal layer and wiring pattern are allowed to be fixed on theceramic substrate. Since this transfer material has a wiring made ofcopper, transfer itself can be produced cheaper that the silver wiring.However, it is necessary to carry out the firing process in anon-oxidization atmosphere by taking the copper wiring into account.

[0491] Therefore, both for a binder for green sheet and a binder for apaste forming a passive component, it is necessary to use a binderhaving an excellent thermal decomposition property such as, for example,methacrylate based acrylic binder, etc.

[0492] Therefore, the transfer materials are used in different ways inaccordance with sintering conditions of a green sheet that forms asubstrate or the ceramic forming the passive component.

[0493] The conditions for heating and pressing treatment can bedetermined appropriately. However, the heating and pressing usually canbe carried out under the pressure of 9.8×10⁵ to 9.8×10⁷ Pa (10 to 200kgf/cm²), at the temperature of 70 to 100° C. for 2 to 30 minutes.Therefore, a wiring pattern can be formed without damaging the greensheet.

[0494] The conditions for the treatment for removing the binder isappropriately determined in accordance with the kinds of binders, metalforming the wiring pattern, or the like. However, usually, the treatmentis carried out by the electric furnace under the conditions of atemperature of 500 to 700° C., temperature rising time of 10 hours, andmaintaining time of 2 to 5 hours.

[0495] The conditions for firing are appropriately determined inaccordance with the kinds of the ceramic and the like. However, usually,the firing is carried out in a belt furnace, at a temperature of 860 to950° C. for 30 to 60 minutes in the air or in nitrogen.

[0496] Furthermore, the second method for producing the wiring substratewill be explained. When the multi-layered circuit substrate as shown inFIG. 25 is produced, single layered circuit substrates laminatedsequentially as mentioned above, and interlayer portion is adhered.Needless to say, it is possible to harden two or more of single layeredcircuit substrates in one operation.

[0497] For example, when the circuit substrate having a base materialsheet including a thermosetting resin is laminated, respectively asshown in FIGS. 26A to 26C, similar to the above, by transferring onlythe component wiring pattern to the base material sheet, a singlelayered circuit substrate as shown in FIGS. 26A′ to 26C′ can beobtained. The laminate of the single layered circuit substrates isheated and pressed at the curing temperature of the thermosetting resinso as to cure the thermosetting resin, thus to fix the adhesion betweenthe circuit substrates.

[0498] When the heating and pressing temperature for transferring thewiring layer in the single layer wiring substrate is set to be 100° C.intentionally, even after the transfer, the base material sheet can beused as a prepreg. Thus, it is possible to produce a multi-layeredwiring substrate by fixing the adhesion between the substrates after thesingle layer wiring substrates are laminated instead of sequentiallylaminating the single layer wiring substrates.

[0499] Furthermore, for example, in the case of laminating the ceramiccircuit substrate having a base material sheet including a ceramic,similar to the above, after only the component wiring pattern istransferred to the base material sheet, this single layered ceramiccircuit substrate is laminated and heated and pressed. Thus, firing ofthe ceramic and the adhesion fixation between the circuit substrates canbe carried out at the same time.

[0500] The number of the laminated layers in the multi-layered circuitsubstrates (FIG. 25) is not particularly limited. However, the number isusually 4 to 10 layers, and as many as 12 layers is also possible.Furthermore, the total thickness of the multi-layered circuit substrateis usually 500 to 1000 μm.

[0501] The surface of the circuit substrates forming inside layers otherthan the outermost layer of the multi-layered circuit substrate (FIG.25) may be flat instead of a convex and concave portion in which thewiring pattern is embedded in its concave portion by taking the electricconnection structure by inner via into account. In order to obtain thisstructure intentionally, the use of the fourth or fifth transfermaterial is one solution. Furthermore, the outer most layer of themulti-layered substrate may be a flat circuit substrate, the surface ofwhich is flat. However, if the surface has a concave portion, and thesecond metal layer etc. is formed in the bottom of the concave portionin the wiring substrate, it is possible to mount a semiconductor chipetc. as shown in FIG. 24H more easily.

EXAMPLE

[0502] Hereinafter, the fifth to twelfth embodiments of the presentinvention will be described in detail by way of Examples.

EXAMPLE 11

[0503]FIGS. 22A to 22G′ are cross-sectional views schematically showingone example of a process for producing the fourth transfer material ofthe present invention.

[0504] As shown in FIGS. 22A to 22E and FIGS. 22A to 22E′, a transfermaterial including passive components 2405, 2406 and 2407(FIG. 22E), anda transfer material including a semiconductor chip that is an activecomponent 2408 (FIG. 22E′) were produced.

[0505] As shown in FIG. 22A, as a first metal layer 2401, anelectrolytic copper foil having a thickness of 35 μm was prepared.First, a copper salt raw material was dissolved in an alkaline bath andallowed to be electrodeposited to a rotation drum so that it had a highelectric current density. Thus, a metal layer (copper layer) was formed.This copper layer was rolled up continuously so as to form anelectrolytic copper foil.

[0506] Next, as shown in FIG. 22B, a pattern opposite to the wiringpattern was formed by using a dry film resist 2404. Thereafter, as shownin FIG. 22C, a metal layer for forming a wiring pattern made of silver2403 was laminated by electrolytic plating on the first metal layer 2401in a thickness of 9 μm. Thus, two-layered structure as shown in FIG. 22Dwas produced. The surface thereof was subjected to a rougheningtreatment so that the average roughness (Ra) of the center line of thesurface was about 4 μm.

[0507] Next, the portion corresponding to the passive components(inductor, capacitor, and resistor) were formed by a screen printingmethod. In a configuration of this Example, the passive componentscapable of being sintered together were employed so that they aremounted on a ceramic substrate.

[0508] As the inductor 2405, a paste was formed by kneading a Ni—Znferrite powder, 5 weight % of acrylic resin (Kyoeisya Kagaku Co., Ltd.;polymerization degree 100 cps), 15 weight % of terpineol (manufacturedby Kanto Chemical Co., Inc), and 5 weight % of BBP (manufactured byKanto Chemical Co., Inc) by using a triple roller.

[0509] As the capacitor 2406, similarly, a paste was formed by kneadingPb-based perovskite compound (PbO—MgO—Nb₂O₅—NiO—WO₃—TIO₂) powder byusing a triple roller. As the resistor 2407, similarly, a paste wasformed by mixing 5 to 50 weight % of ruthenium oxide powder with 95 to50 weight % of low melting point borosilicate glass.

[0510] The inductor 2405, capacitor 2406, and resistor 2407 formed ofthese pastes were produced on the two layered structure shown in FIG.22D by a printing method by using a predetermined shaped mask as shownin FIG. 22E. After printing, they were dried at 90° C. for 20 minutes.

[0511] When the transfer, firing and fixation were carried out on theceramic substrate, an active component such as semiconductor chip, etc.was not formed on the transfer material (see FIG. 22E). However, whenthe transfer is carried out on the resin substrate, an active componentsuch as semiconductor chip 2408 etc. can be formed (see FIG. 22E′).After flip-chip mounting, an underfill 2411 may be used for sealing agap between a semiconductor chip 2408 and a wiring pattern 2412 andcompletely cured for integration at 150° C.

[0512] By using the transfer material shown in FIG. 22E, as shown inFIGS. 22F to 22G, a ceramic circuit component was produced.

[0513] First, a substrate 2409 on which a wiring pattern is transferredwas prepared. This substrate 2409 was produced by preparing a lowtemperature sintering ceramic green sheet A including a low temperaturesintering ceramic material and an organic binder, providing thesubstrate 2409 with via holes, and filling the via holes with aconductive paste 2410. Hereinafter, the component compositions of thegreen sheet A are described.

[0514] (Component Composition of the Green Sheet A)

[0515] mixture of ceramic powder Al₂O₃ and borosilicate glass (MLS-1000manufactured by Nippon Electric Glass Co., Ltd.) 88 weight %

[0516] carboxylic acid based acrylic binder (Olicox, Kyoeisya KagakuCo., Ltd.) 10 weight %

[0517] BBP (manufactured by Kanto Chemical Co., Inc.) 2 weight %

[0518] Each of the above-mentioned component was weighed so as to havethe above-mentioned composition weight ratio. A solvent of toluene wasadded into the mixture of the above-mentioned components so that theviscosity of the slurry mixture was about 20 Pa.s, and then rotated andmixed by using alumina balls in a pot at the rotation rate of 500 rpmfor 48 hours so as to form into a slurry.

[0519] Next, as a mold release film, PPS film having a thickness of 75μm was prepared. On the PPS film, the slurry was formed into a filmsheet by the doctor blade method at a gap of about 0.4 mm. The toluenesolvent in the sheet was allowed to volatilize so as to remove the PPSfilm, thus to form a green sheet A having a thickness of 220 μm. Sincein this green sheet A a plasticizer BBP was added into the carboxylicacid based acrylic binder, this sheet had high strength, flexibility andexcellent thermal decomposition property.

[0520] This green sheet A was cut in a predetermined size by the use ofits flexibility, and provided with through holes (via holes) having adiameter of 0.15 mm at equally intervals with a pitch of 0.2 to 2 mm byusing a punching machine. Then, the through holes were filled with aconductive paste for filling via holes by a screen printing method.Thus, the substrate 2409 was produced. The conductive paste 2410 to beused was obtained by kneading the following materials at the followingcompositions by using a triple roller.

[0521] [Conductive Paste 2410]

[0522] spherical silver particles (Mitsui Mining & Smelting Co., Ltd.,particle diameter of 3 μm) 75 weight %

[0523] acrylic resin (manufactured by Kyoeisya Kagaku Co., Ltd.,polymerization degree 100 cps) 5 weight %

[0524] terpineol (manufactured by Kanto Chemical Co., Inc.) 15 weight %

[0525] BBP (manufactured by Kanto Chemical Co., Inc.) 5 weight %

[0526] Next, as shown in FIG. 22F, the transfer material produced inExample 22E was placed so that it was brought into contact with bothsurfaces of the substrate 2409, and a heating and pressing treatment wascarried out by a thermal press method at a pressing temperature of 70°C. and a pressure of about 5.88×10⁶ Pa (60 kgf/cm) for 5 minutes.Herein, in the capacitor 2406, an electrode pattern 2411 may be formedpreviously on the substrate 2409 by a transfer method etc. so that thedielectric layer was sandwiched between the upper and lower sides of theelectrode surface. This method is possible only with the transfermaterial of the present invention on which the capacitor is formed byprinting and was not possible in the conventional method in which thedielectric layer was printed on the substrate green sheet.

[0527] With this heating and pressing treatment, an acrylic resin in thesubstrate 2409 was fused and softened. Thus, the wiring layer 2403 ofthe second metal layer and circuit components 2405, 2406 and 2407 wereembedded into the substrate 2409.

[0528] After the laminate of this substrate 2409 and the transfermaterial was cooled, the first metal layer 2401 that is a carrier oftransfer material was peeled off from the laminate, and thereby acircuit substrate sheet, on both surfaces of which the wiring layer 2403and the circuit components 2405, 2406 and 2407 were transferred, wasobtained.

[0529] Then, the circuit substrate sheet was sandwiched by an aluminagreen sheet formed of an alumina inorganic filler that is not sinteredat the firing temperature so as to form a laminate, and the laminate wassubjected to a binder removing process and firing in the air, andthereby fixed. First, in order to remove the organic binder in thecircuit substrate (FIG. 22G), the laminate was heated by an electricfurnace up to 500° C. at the raising temperatures at 25° C./hour,treated at 500° C. for 2 hours. Then, the wiring substrate in which thebinder was removed was burned at 900° C. for 20 minutes in the air. Thefiring conditions were set to be a temperature rising time of 20minutes, temperature falling time of 20 minutes and in/out total time of60 minutes. After firing, the alumina green sheet was easily removed.

[0530] This wiring substrate had a flat mounted surface after firing. Onthe wiring layer 2403 of this circuit substrate (FIG. 22G), a goldplating layer may be formed.

[0531] Warp, cracks, distortion did not occur in this circuit substrate.This is partly because a non-shrinkage sintering process was used in aplane direction. This process made it possible to burn the copper foilwiring and ceramic substrate simultaneously. The mounting position ofeach of the circuit components (inductor, capacitor and resistor) wasaccurate. Thus, a precise circuit substrate as designed was produced inone transfer.

[0532] Furthermore, when capacitor high temperature load reliabilitytest (125° C., 50V, 1000 hours) was carried out, the insulatingresistance of the dielectric layer of the capacitor 2406 was notdeteriorated and 10⁶Ω or more of insulating resistance was secured.Furthermore, the dielectric constant was 5000 for the dielectric layer,and 8.1 for the substrate layer. An inductance of the inductor 2405 wassecured to be 0.5 μH. Furthermore, the resistance value of the resistor2407 was permitted to be a desired value ranging from 100Ω to 1 MΩ.

[0533] Thus, the use of the transfer material of the present inventionfacilitated formation of circuit components including passive componentssuch as an inductor, a capacitor, and a resistor, etc.

[0534] In addition, it is advantageous in the present invention that bya non-shrinkage sintering process in the plane direction and a transferprocess of a high-density conductive pattern by plating, a wiring havingan extremely high dielectric constant can be attained and that by usingsilver for the wiring metal, a binder removing process and firing can beperformed in the air. In particular, since the latter process can beemployed, the composition of a substrate, each composition of passivecomponents such as an inductor, a capacitor, and resistor, etc, can beselected from the wide range.

[0535] FIGS. 22F′ and 22G′ show the case where the transfer materialshown in FIG. 22E′ is transferred, mounted and fixed to a resinsubstrate. As in the case of the ceramic green sheet, it was confirmedthat transfer and mounting were carried out in one time.

EXAMPLE 12

[0536]FIGS. 23A to 23H are cross-sectional views schematically showingone example of a process for producing a wiring substrate by using thefifth transfer material.

[0537] The fifth transfer material was produced by the way shown inFIGS. 23A to 23F.

[0538] First, as shown in FIG. 23A, as a first metal layer 2501, anelectrolytic copper foil having a thickness of 35 μm was prepared.Specifically, a copper salt raw material was dissolved in an alkalinebath and allowed to be electrodeposited to a rotation drum so that ithad a high electric current density. Thus, a metal layer (copper layer)was formed. This copper layer was rolled up continuously so as to forminto an electrolytic copper foil.

[0539] Next, a thin nickel-phosphorous alloy plating layer was formed onthe surface of the first metal layer 2501 as a peel layer 2502. As ametal layer for forming a wiring pattern 2503, an electrolytic copperfoil that is the same as the first metal layer 2501 was laminated in athickness of 9 μm by electrolytic plating, to thus form the second metallayer 2503. Thus, a three-layered laminate was produced (FIG. 23A).

[0540] The surface of the laminate was subjected to a rougheningtreatment so that the average roughness (Ra) of the center line of thesurface was about 4 μm. The roughening treatment was carried out byprecipitating fine copper powder on the electrolytic copper foil.

[0541] Next, a dry film resist (DFR) 2504 was placed on the laminate byphotolithography as shown in FIG. 23B, and exposure and development ofthe wiring pattern portion were carried out as shown in FIG. 23C.Thereafter, the second metal layer 2503 of the laminate was etched by achemical etching process (immersing in an aqueous solution of ferricchloride) so as to form a desired wiring pattern as shown in FIG. 23D.With such an etchant, only the second metal layer was etched and thethin nickel-phosphorous alloy layer that is the peel layer was notetched.

[0542] Thereafter, as shown in FIG. 23E, the remaining dry film resistwas removed by a peeling agent. Thus, a transfer material was obtained.

[0543] Next, the portion corresponding to the passive components wasformed by a screen printing method. In a configuration of this Example,the passive components capable of being sintered together were employedso that they are mounted on a ceramic substrate.

[0544] As the inductor 2505, a paste was formed by kneading Ni—Znferrite powder, 5 weight % of acrylic resin (Kyoeisya Kagaku Co., Ltd.;polymerization degree: 100 cps), 15 weight % of terpineol (manufacturedby Kanto Chemical Co., Inc), and 5 weight % of BBP (manufactured byKanto Chemical Co., Inc) by using a triple roller.

[0545] As the capacitor 2506, similarly, a paste was formed by kneadingPb-based perovskite compound (PbO—MgO—Nb₂O₅—NiO—WO₃—TIO₂) powder byusing a triple roller.

[0546] As the resistor 2507, similarly, a paste was formed by mixing 5to 50 weight % of ruthenium oxide powder with 95 to 50 weight % of lowmelting point borosilicate glass.

[0547] By using these pastes, by using a predetermined shaped mask, theinductor 2505, capacitor 2506, and resistor 2507 were formed on thetransfer material shown in FIG. 23E by a printing method as shown inFIG. 23F. By using the transfer materials, a ceramic substrate wasproduced by the method shown in FIGS. 23G to 23H.

[0548] First, a substrate 2508 was prepared. This substrate 2508 wasproduced by preparing a low temperature sintering ceramic green sheet Bincluding a low temperature sintering ceramic material and an organicbinder, providing the substrate 2508 with via holes, and filling the viaholes with a conductive paste 2509. Hereinafter, the componentcompositions of the green sheet B are described.

[0549] [Component Composition of the Green Sheet B]

[0550] mixture of ceramic powder Al₂O₃ and borosilicate glass (MLS-1000manufactured by Nippon Electric Glass Co., Ltd.) 88 weight %

[0551] methacrylic acid based acrylic binder (Olicox 7025, KyoeisyaKagaku Co., Ltd.) 10 weight %

[0552] BBP (manufactured by Kanto Chemical Co., Inc.) 2 weight %

[0553] Each of the above-mentioned component was weighed so as to havethe above-mentioned composition weight ratio. A solvent of toluene wasadded into the mixture of the above-mentioned components so that theviscosity of the slurry mixture was about 20 Pa.s, and then rotated andmixed by using alumina balls in a pot at the rotation rate of 500 rpmfor 48 hours so as to form into a slurry.

[0554] Next, as a mold release film, a PPS film having a thickness of 75μm was prepared. On the PPS film, the slurry was formed into a filmsheet by the doctor blade method at a gap of about 0.4 mm. The toluenesolvent in the sheet was allowed to volatilize so as to remove the PPSfilm, thus to form a green sheet B having a thickness of 220 μm. Sincein this green sheet B, a plasticizer BBP was added into the methacrylicacid based acrylic binder that is an organic binder, this sheet hadflexibility and an excellent thermal decomposition property.

[0555] This green sheet B was cut in a predetermined size by the use ofits flexibility, and provided with through holes (via holes) having adiameter of 0.15 mm at equally intervals with a pitch of 0.2 to 2 mm byusing a punching machine. Then, the through holes were filled with aconductive paste 2509 for filling via holes by a screen printing method.Thus, the substrate 2508 was produced by the above-mentioned process.The conductive paste 2509 to be used was obtained by kneading thefollowing materials at the following compositions by using a tripleroller.

[0556] [Conductive Paste 2509]

[0557] spherical silver particles (Mitsui Mining & Smelting Co., Ltd.,particle diameter of 3 μm) 75 weight %

[0558] acrylic resin (manufactured by Kyoeisya Kagaku Co., Ltd.,polymerization degree 100 cps) 5 weight %

[0559] terpineol (manufactured by Kanto Chemical Co., Inc.) 15 weight %

[0560] BBP (manufactured by Kanto Chemical Co., Inc.) 5 weight %

[0561] Next, the transfer material produced as mentioned above (FIG.23F) was placed so that it was brought into contact with both surfacesof the substrate 2508, and a heating and pressing treatment was carriedout by a thermal press at a pressing temperature of 70° C. and apressure of about 5.88×10⁶ Pa (60 kgf/cm²) for 5 minutes. Herein, in thecapacitor 2506, an electrode pattern 2510 may be formed previously onthe substrate 2508 by a transfer method etc. so that the dielectric wassandwiched between the upper and lower sides of the electrode surfaces.This method is possible only with the transfer material of the presentinvention on which the capacitor is formed by printing and was difficultin the conventional method in which the dielectric layer was printeddirectly on the substrate green sheet.

[0562] With this heating and pressing treatment, an acrylic resin in thesubstrate 2508 was fused and softened. Thus, the second metal layer 2503that is a wiring pattern and circuit components (the inductor 2505, thecapacitor 2506, and the resistor 2507) were embedded into the substrate2508.

[0563] After such a laminate of the transfer material and this substrate2508 was cooled, the first metal layer 2501 that is a carrier was peeledoff from the laminate, thereby a circuit substrate sheet both surfacesof which the second metal layer 2503 that is a wiring pattern and thecircuit components (the inductor 2505, the capacitor 2506, and theresistor 2507) were transferred was obtained.

[0564] Then, the circuit substrate sheet was sandwiched by an aluminagreen sheet formed of only an alumina inorganic filler, which is notsintered at the firing temperature of the substrate so as to form alaminate, and the laminate was subjected to a binder removing processand firing in an atmosphere of nitrogen, and thereby fixed.

[0565] First, in order to remove the organic binder in the circuitsubstrate (FIG. 23H), the laminate was heated by an electric furnace upto 600° C. with raising temperatures at 25° C./hour, and treated at 600°C. for 2 hours. Then, the wiring substrate in which the binder wasremoved was burned at 900° C. for 20 minutes by a belt furnace in anatmosphere of nitrogen. The firing condition was set to be a temperaturerising time of 20 minutes, temperature falling time of 20 minutes andin/out total time of 60 minutes. After firing, the alumina green sheetwas easily removed.

[0566] This wiring substrate (FIG. 23H) had a flat mounted surface. Onthe wiring layer 2503 of this circuit substrate (FIG. 23H), a goldplating layer may be formed.

[0567] Warp, cracks, distortion did not occur in this circuit substrate.This is partly because a non-shrinkage sintering process was used in aplane direction. This made it possible to burn the copper foil wiringand ceramic substrate simultaneously. Also, the mounting position ofeach circuit component was accurate. Thus, a precise circuit substrateas designed was produced in one transfer.

[0568] Furthermore, when capacitor high temperature load reliabilitytest (125° C., 50V, 1000 hours) was carried out, the insulatingresistance of the dielectric layer of the capacitor 2506 was notdeteriorated and the 10⁶Ω or more of insulating resistance was secured.Furthermore, the dielectric constant was 5000 for the dielectric layer,and 8.1 for the substrate layer. An inductance of the inductor 2505 wassecured to be 0.5 μH. Furthermore, the resistance value of the resistor2507 could be a desired value ranging from 100Ω to 1 MΩ.

[0569] Thus, the use of the transfer material of the present inventionfacilitated formation of circuit components including an inductor, acapacitor, and a resistor, etc.

EXAMPLE 13

[0570]FIGS. 24A to 24H are cross-sectional views schematically showingone example of a process for producing a wiring substrate by using thesixth transfer material.

[0571] The sixth transfer material was produced by a method shown inFIGS. 24A to 24H.

[0572] First, as a first metal layer 2601, an electrolytic copper foilhaving a thickness of 35 μm was prepared. A copper salt raw material wasdissolved in an alkaline bath and allowed to be electrodeposited to arotation drum so that it had a high electric current density. Thus, ametal layer (copper layer) was formed. This copper layer was rolled upcontinuously so as to form into an electrolytic copper foil.

[0573] Next, an adhesive agent formed of an organic layer was appliedthinly on the surface of the first metal layer 2601 as a peel layer2602. As a second metal layer 2603 for forming a wiring pattern, anelectrolytic copper foil same as the first metal layer 2601 waslaminated in a thickness of 9 μm by electrolytic plating. Thus,three-layered laminate was produced (FIG. 24A).

[0574] The surface of the laminate was subjected to a rougheningtreatment so that the average roughness (Ra) of the center line of thesurface was about 4 μm. The roughening treatment was carried out byprecipitating fine copper powder on the electrolytic copper foil.

[0575] Next, as shown in FIG. 24B, a dry film resist (DFR) 2604 wasplaced on the laminate by photolithography and exposure and developmentof the wiring pattern portion was carried out as shown in FIG. 24C.Thereafter, as shown in FIG. 24D, not only the second metal layer 2602but also the surface portion of the first metal layer 2601 of thelaminate were etched by a chemical etching process (immersing in anaqueous solution of ferric chloride) so as to form a desired wiringpattern.

[0576] Thereafter, the DFR 2604 was peeled off by a peeling agent so asto produce a three-layered structure shown in FIG. 24E. Since the firstmetal layer and the second metal layer are formed of the same metal,copper, it is possible to form a convex portion on not only the secondmetal layer but also a part of the first metal layer. This structure ischaracterized in that the wiring pattern is processed also in the firstmetal layer that is a carrier layer. Moreover, in this example, as thepeel layer, an organic layer was used. The peel layer is not necessarilylimited thereto, and for example, a nickel plating layer etc. may beused. In this case, the transfer material having the same effect can beobtained.

[0577] In this three-layered structure, the peel layer 2602 that adheresthe first metal layer 2601 to the second metal layer 2603 for formingthe wiring pattern was weak in adhesive strength itself but excellent inetch resistance property. Thus, even if the entire three-layeredstructure was subjected to an etching process, the wiring pattern wasformed without peeling of the interlayer portion. The adhesive strengthbetween the first metal layer 2601 and the second metal layer 2603 viathe peel layer 2602 was 40 N/m (gf/cm), exhibiting an excellent peelingproperty.

[0578] Next, a circuit component was formed by a screen printing method.In a configuration of this Example, the passive components capable ofbeing sintered together were employed so that they are mounted on aresin substrate.

[0579] As the inductor 2605, a paste was formed by kneading a Ni—Znferrite powder, 10 weight % of liquid epoxy resin (EF-450 manufacturedby Nippon Rec Co. Ltd.), 0.3 weight % of coupling agent (46B, titanatebased coupling agent manufactured by Ajinomoto Co., Inc.) by using akneader revolving both on its orbital and on its own axis at high speed.

[0580] Moreover, a paste including magnetic alloy powder, was sendustpowder as a filler was produced. As the capacitor 2606, similarly, apaste was formed by kneading Pb-based perovskite compound(PbO—MgO—Nb₂O₅—NiO—WO₃—TIO₂) powder by using a triple roller. As theresistor 2607, similarly, a paste was formed having the similarconfiguration with the content of carbon content by varying the contentof carbon.

[0581] The sixth transfer material was produced by using the circuitcomponents formed of these pastes were produced on the three-layeredstructure shown in FIG. 24E by a printing method by using apredetermined shaped mask as shown in FIG. 24F. After printing, theywere dried at 90° C. for 20 minutes.

[0582] Moreover, on the transfer material, a wiring pattern 2613 wasformed so that a semiconductor chip 2608 is mounted on the wiringsubstrate after transfer by using the transfer material.

[0583] Thereafter, as shown in FIGS. 24G to 24H, a print circuitsubstrate was produced as follows.

[0584] First, a substrate 2610 was prepared. This substrate 2601 wasproduced by preparing a base material sheet formed of a compositematerial, providing the substrate 2601 with via holes, and filling thevia holes with a conductive paste 2611. Hereinafter, the componentcompositions of the base material sheet 2610 are described.

[0585] [Component Composition of the Substrate Sheet 2610]

[0586] Al₂O₃ (AS-40 manufactured by Showa Denko K. K., average particlediameter of 12 μm) 90 weight %

[0587] liquid epoxy resin (EF-450, manufactured by Nippon Rec Co. Ltd.)9.5 weight %

[0588] carbon black (manufactured by Toyo Carbon) 0.2 weight %

[0589] coupling agent (46B, titanate based coupling agent manufacturedby Ajinomoto Co., Inc.) 0.3 weight %

[0590] Each of the above-mentioned components was weighed so as to havethe above-mentioned composition weight ratio. A solvent of methyl ethylketone as a solvent for adjusting viscosity was added into the mixtureof the above-mentioned components so that the viscosity of the slurrymixture was about 20 Pa.s, and then rotated and mixed by using aluminaballs in a pot at the rotation rate of 500 rpm for 48 hours so as toform into a slurry.

[0591] Next, as a mold release film, a PET film having a thickness of 75μm was prepared. On the PET film, the slurry was formed into a filmsheet at a gap of about 0.7 mm by a doctor blade method. The film sheetwas allowed to stand for 1 hour at 100° C. so as to volatilize themethyl ethyl ketone solvent and to remove the PET film, thus to forminto a base material sheet 2601 having a thickness of 350 μm. Since thesolvent was removed at 100° C., the epoxy resin was kept uncured and thebase material sheet had a flexibility.

[0592] This base material sheet was cut in a predetermined size by theuse of its flexibility, and provided with through holes (via holes)having a diameter of 0.15 mm at equally intervals with a pitch of 0.2 to2 mm. Then, the through holes were filled with a conductive paste 2611for filling via holes by a screen printing method. Thus, the substrate2610 was produced. The conductive paste 2611 to be used was obtained bymixing and kneading the following materials at the below mentionedcompositions by using a triple roller.

[0593] [Conductive Paste 2611]

[0594] spherical copper particles (Mitsui Mining & Smelting Co., Ltd.,particle diameter of 2 μm) 85 weight %

[0595] bisphenol A epoxy resin (Epicoat 828 manufactured by Yuka ShellEpoxy) 3 weight %

[0596] glycidyl ester based epoxy resin (YD-171 manufactured by TotoKasei) 9 weight %

[0597] amine adduct hardening agent (MY-24 manufactured by AjinomotoCo., Inc.) 3 weight %

[0598] Next, as shown in FIG. 24G, the transfer material was placed sothat the transfer material produced in the above (FIG. 24F) was broughtinto contact with both surfaces of the substrate 2610, heated andpressed by a thermal press at a pressing temperature of 120° C. and apressure of 9.8×10⁵ Pa (10 kgf/cm) for 5 minutes.

[0599] In the capacitor 2610, when the dielectric layer is sandwichedbetween the upper and lower electrodes, an electrode pattern 2612 can betransferred to the substrate previously. Such a method is possible onlywith the transfer material of the present invention on which thecapacitor is formed by printing and was difficult in the conventionalmethod in which the dielectric layer was printed on the composite sheetincluding a ceramic as a filler.

[0600] With this heating and pressing treatment, an epoxy resin in thesubstrate 2610 (an epoxy resin in the base material sheet and theconductive paste 2611) was fused and softened (FIG. 24H). Thus, thecircuit components pattern (the inductor 2605, the capacitor 2606, andthe resistor 2607) and the second metal layer 2603 as a wiring patternwere embedded in the substrate 2610. The heating temperature was furtherraised and treated at 175° C. for 60 minutes, thereby the epoxy resinwas cured. Thereafter, a semiconductor chip 2608 was flip-chip mountedon the wiring 2613.

[0601] Thus, the base material sheet was adhered to the entire circuitcomponent pattern strongly. Furthermore, the conductive paste 2611 andeach of the circuit components was electrically connected (inner viaconnection) and adhered to each other strongly.

[0602] Thereafter, a first metal layer 2601 that is a carrier layer andthe peel layer 2602 were peeled off, thereby a wiring substrate bothsurfaces of which had a circuit component patterns (inductor 2605,capacitor 2606, and resistor 2607) and wiring patterns (second metallayer 2603) was obtained. On the surfaces of the wiring substrate, theconcave portion corresponding to the depth of the etched portion of thefirst metal layer 2603 was formed in the transfer material, and all thewiring patterns and the circuit component patterns were formed at thebottom of the concave portion.

[0603] Thus, the use of this transfer material facilitated peeling ofthe adhesive plane between the first metal layer 2601 and the secondmetal layer 2603 via the peel layer 2602, and enabled transfer of onlythe second metal layer 2603 and circuit component patterns (inductor2605, capacitor 2606, and resistor 2607) to the substrate when thesecond transfer 2603 was transferred to the substrate 2610.

[0604] In this Example, the first metal layer 2601 that is a carrierlayer was formed of a copper foil having a thickness of 35 μm, and evenif the transfer material of the substrate 2610 was deformed at the timeof transfer, the carrier layer was resistant to the deformation stress.On the other hand, in the transfer material in this example, the wiringportion has a convex shape, when the transfer material is pressed ontothe base material sheet, the base material is likely to flow into theconcave portion, thus suppressing the deformation stress that distortsthe pattern in the vertical direction. Therefore, the pattern distortionin this example was 0.08% that is an amount generated by the curing andshrinking of the base material.

[0605] Moreover, in this Example, the peel layer formed of an organiclayer was used. The peel layer is not necessarily limited thereto, andfor example, plating layer such as a Ni plating layer etc. having athickness of 200 nm or less may be used. In this case, the transfermaterial having the same effect was obtained.

[0606] Furthermore, the semiconductor chip 2608 was flip-chip mounted onthe wiring 2613 easily by positioning the bumps with respect to thewiring 2613 formed on the concave portion.

[0607] The mounting position of each of the circuit components(inductor, capacitor and resistor) was accurate. Thus, a precise circuitsubstrate as designed was produced in one transfer. The wiring substrateof this Example was excellent in connection between the semiconductorchip 2608 and the wiring 2613. Also, a capacitor 2606 that was mountedso that it functioned as a bypass capacitor functioned excellently.Furthermore, when capacitor high temperature load reliability test (125°C., 50V, 1000 hours) was carried out, the insulating resistance of thedielectric layer of the capacitor 2606 was not deteriorated and the 10⁶Ωor more of insulating resistance was secured.

[0608] Furthermore, the dielectric constant was 200 for the dielectriclayer, and 8.1 for the substrate layer. An inductance of the inductor2605 was secured to be 0.5 μH or more, that is a sufficient value, evenwhether it is ferrite or a magnetic alloy. Furthermore, the resistancevalue of the resistor 2607 could be a desired value ranging from 100Ω to1 MΩ.

[0609] Thus, the use of the transfer material of the present inventionfacilitates the formation of circuit components including wiringpattern, active components such as a semiconductor chip, and passivecomponents such as an inductor, capacitor, and resistor, etc.

EXAMPLE 14

[0610] With the fourth to sixth transfer materials of the presentinvention, and by using the substrate formed of composite materialproduced by the same method as in Example 13, a multi-layered wiringsubstrate was produced as shown in FIG. 25. FIG. 26 is a cross sectionalview schematically showing the method for producing each layer.

[0611] As shown in FIG. 26, reference numerals 2800A, 2800B and 2800Cdenote transfer materials, respectively. 2800A denotes a transfermaterial on which mainly a resistor is formed by printing. 2800B denotesa transfer material in which mainly a dielectric layer that serves as acapacitor 2804 is formed by printing. 2800C is transfer material inwhich mainly a magnetic layer that serves as the inductor 2805 wasformed by printing.

[0612] Furthermore, in this Example, as shown in FIGS. 26A to 26C, innervia holes in the substrate sheet 2806 are filled with the conductivepaste 2807. Since the configuration of this was the same as in Example13, the detailed explanation is not repeated herein.

[0613] Furthermore, the wiring pattern layer 2808 formed on the surfaceof the top layer of the multi-layered substrate and one electrode 2809of the capacitor 2804 were formed on the substrate previously. Moreover,the transfer material to be used for the transfer has the sameconfiguration of the transfer material of the present invention.

[0614] Conventionally, when passive components formed by printing areincorporated into a multi-layered substrate, an individual component wasformed by printing on the substrate green sheet. However, in such aprocess, the unevenness having a thickness of a several tens μm occurson the surface of the substrate. Therefore, if many layers are laminatedfor obtaining a multi-layered structure, when sintered and pressed, anexternal terminal of the outer capacitor etc. is deformed as squashed,thus deteriorating the insulating property. Thus, the short circuit ofthe capacitor was generated frequently.

[0615] In this Example, as shown in FIG. 26B, the electrode 2802 and thedielectric layer 2804 formed on the transfer material 2800B were pressedwith positioning onto the electrode patterns 2809 that were previouslyformed on the substrate sheet 2806. At this time, these electrode 2802and dielectric layer 2804 are embedded in the substrate sheet 2806having an excellent in fluidity. As shown in FIG. 26B′, a single layeredwiring substrate was produced without unevenness on the surface.

[0616] Similarly, when the transfer was carried out by using thetransfer materials 2800A and 2800C, no unevenness occur. As shown inFIGS. A′ and C′, a flat level was formed respectively.

[0617] Finally, the single layered wiring substrates shown in FIGS. 26A′to 26C′ and the wiring substrate to which the wiring patterns weretransferred on both surfaces as shown in FIG. 26D′ were laminated into asheet, and the sheet was cured in one heating and pressing treatment.Thereby, each layer in which the circuit component such as an inductor,capacitor, and resistor are integrated, thus a multi-layered circuitsubstrate as shown in FIG. 25 can be produced. In this example, eachlayer has a flat surface without unevenness, and thus a laminatingprocess can be carried out easily.

[0618] As mentioned above, the fourth to sixth transfer materials of thepresent invention allow a fine wiring pattern as well as circuitcomponents such as inductor, capacitor, and resistor etc. to be formedby a printing method and to be transferred in one transfer process.Therefore, easy and accurate mounting to the substrate can be possible.Furthermore, since the wiring pattern and component pattern are mountedby transfer, the wiring pattern and the component patterns can beembedded without occurring unevenness. This facilitates the subsequentlaminating process without disconnection of the wiring or damage of thepattern shape.

[0619] Moreover, in the fifth to twelfth embodiments and Examples 11 to14, the transfer material on which all of the inductor, capacitor, andresistor are formed is described, however, all of these components arenot necessarily formed.

[0620] The invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof Theembodiments disclosed in this application are to be considered in allrespects as illustrative and not restrictive, the scope of the inventionbeing indicated by the appended claims rather than by the foregoingdescription, all changes that come within the meaning and range ofequivalency of the claims are intended to be embraced therein.

What is claimed is:
 1. A transfer material comprising at least threelayers of a first metal layer as a carrier, a second metal layer as awiring pattern, a peel layer that is sandwiched between the first metallayer and the second metal layer and allows the first metal layer andthe second metal layer to be adhered releasably, wherein a convexportion corresponding to the wiring pattern is formed on the surfaceportion of the first metal layer, and the peel layer and the secondmetal layer are formed on a region of the convex portions.
 2. Thetransfer material according to claim 1, wherein each of the first metallayer and the second metal layer comprises at least one metal selectedfrom the group consisting of copper, aluminum, silver, and nickel. 3.The transfer material according to claim 1, wherein the first metallayer and the second metal layer comprise the same metal component. 4.The transfer material according to claim 2, wherein the first metallayer and the second metal layer comprise a copper foil.
 5. The transfermaterial according to claim 4, wherein the peel layer comprises amaterial to be etched with a copper etching liquid.
 6. The transfermaterial according to claim 1, wherein a height of the convex portion inthe first metal layer is 1 to 12 μm.
 7. The transfer material accordingto claim 1, wherein a thickness of the peel layer is 1 μm or less. 8.The transfer material according to claim 1, wherein the peel layer is anorganic layer or a metal plating layer.
 9. The transfer materialaccording to claim 8, wherein the peel layer is an Au plating layer. 10.The transfer material according to claim 1, wherein an adhesive strengthbetween the first metal layer and the second metal layer via the peellayer is 50 N/m or less.
 11. The transfer material according to claim 1,wherein a thickness of the first metal layer is 4 to 40 μm and athickness of the second metal layer is 1 to 35 μm.
 12. The transfermaterial according to claim 1, further comprising a third metal layer onthe second metal layer.
 13. The transfer material according to claim 12,wherein a thickness of the third metal layer is 2 to 30 μm.
 14. Thetransfer material according to claim 12, wherein the first to thirdmetal layers comprise the same metal component.
 15. The transfermaterial according to claim 12, wherein the third metal layer comprisesgold.
 16. The transfer material according to claim 12, furthercomprising a fourth metal layer on the third metal layer, wherein thefourth metal layer comprises a metal component that is chemically stablewith respect to an etching liquid corroding the first to third metallayers.
 17. The transfer material according to claim 16, wherein thefourth metal layer comprises at least one metal selected from the groupconsisting of gold, silver, nickel, tin, bismuth, lead and copper, andhas a thickness of 1 to 10 μm.
 18. The transfer material according toclaim 1, wherein a circuit component is formed by a printing method forelectrically connecting to the second metal layer.
 19. The transfermaterial according to claim 18, wherein the circuit component comprisesat least one component selected from the group consisting of aninductor, a capacitor and a resistor.
 20. The transfer materialaccording to claim 18, wherein the circuit component is formed of amaterial comprising an inorganic filler and a resin composition.
 21. Thetransfer material according to claim 18, wherein the circuit componentis formed of a material comprising an inorganic filler, an organicbinder and a plasticizer.
 22. A transfer material comprising at leasttwo layers of a first metal layer as a carrier, and a second metal layeras a wiring pattern, wherein a circuit component is formed on the firstmetal layer by a printing method for electrically connecting to thesecond metal layer.
 23. The transfer material according to claim 22,wherein a peel layer is formed between the first metal layer and thesecond metal layer, and adheres the first metal layer to the secondmetal layer releasably.
 24. The transfer material according to claim 23,wherein a thickness of the peel layer is 1 μm or less.
 25. The transfermaterial according to claim 23, wherein the peel layer is an organiclayer or a metal plating layer.
 26. The transfer material according toclaim 25, wherein the peel layer is an Au plating layer.
 27. Thetransfer material according to claim 23, wherein an adhesive strengthbetween the first metal layer and the second metal layer via the peellayer is 10 N/m or more and 50 N/m or less.
 28. The transfer materialaccording to claim 22, wherein the circuit component comprises at leastone component selected from the group consisting of an inductor, acapacitor and a resistor.
 29. The transfer material according to claim22, wherein the circuit component is formed of a material comprising aninorganic filler and a resin composition.
 30. The transfer materialaccording to claim 22, wherein the circuit component is formed of amaterial comprising an inorganic filler, an organic binder and aplasticizer.
 31. The transfer material according to claim 22, wherein athickness of the first metal layer is 4 to 100 μm, and a thickness ofthe second metal layer and the circuit component is 1 to 35 μm.
 32. Thetransfer material according to claim 22, wherein a convex and concaveportion is formed on the surface portion of the first metal layer, theconvex portion corresponds to the wiring pattern of the second metallayer, and an upper layer on the first metal layer is formed on theconvex portion.
 33. The transfer material according to claim 32, whereina height of the convex portion in the first metal layer is 1 to 12 μm.34. The transfer material according to claim 22, wherein each of thefirst metal layer and the second metal layer comprises at least onemetal selected from the group consisting of copper, aluminum, silver,and nickel.
 35. The transfer material according to claim 22, wherein thefirst metal layer and the second metal layer comprise the same metalcomponent.
 36. A method for producing a transfer material, comprisingforming a peel layer on a first metal layer, forming a second metallayer on the peel layer, and etching the second metal layer, the peellayer and a surface portion of the first metal layer by a chemicaletching process, thereby forming the second metal layer and the peellayer into a wiring pattern, and at the same time, forming a convex andconcave portion having a convex portion corresponding to the wiringpattern on the surface portion of the first metal layer.
 37. The methodfor producing a transfer material according to claim 36, the methodcomprising, after the second metal layer is formed and before theetching is carried out, (a) forming a plating resist on the second metallayer with the surface portion of the second metal layer exposed in thewiring pattern, (b) forming a third metal layer by plating in a regionwhere the second metal layer is exposed, and (c) peeling off the platingresist; thereafter, etching the second metal layer, the peel layer, andthe surface portion the first metal layer in a region where the thirdmetal layer is not formed by a chemical etching process.
 38. The methodfor producing′ a transfer material according to claim 37, wherein thethird metal layer is formed of a metal component chemically stable withrespect to an etchant used for the chemical etching process, and thethird metal layer is allowed to serve as an etching resist in thechemical etching process.
 39. The method for producing a transfermaterial according to claim 38, wherein the third metal layer is formedof gold or silver.
 40. The method for producing a transfer materialaccording to claim 37, the method comprising, after the third metallayer is formed and before the plating resist is peeled off, forming afourth metal layer on the third metal layer by the use of a metalcomponent chemically stable with respect to an etchant used for thechemical etching process, and thereafter, peeling off the platingresist, and etching the second metal layer, the peeling layer and thesurface portion of the first metal layer in a region where the third andfourth metal layers are not formed, by a chemical etching process. 41.The method for producing a transfer material according to claim 40,wherein the fourth metal layer is formed of a metal component chemicallystable with respect to the etchant used for the chemical etchingprocess, and the fourth metal layer is allowed to serve as an etchingresist in the chemical etching process.
 42. The method for producing atransfer material according to claim 41, wherein the fourth metal layeris formed of gold or silver.
 43. The method for producing a transfermaterial according to claim 36, wherein the second metal layer is formedby electrolytic plating.
 44. The method for producing a transfermaterial according to claim 36, wherein the first metal layer and thesecond metal layer are formed of the same metal component.
 45. Themethod for producing a transfer material according to claim 36, whereina depth of the surface portion of the first metal layer that is etchedby the chemical etching process is 1 to 12 μm.
 46. The method forproducing a transfer material according to claim 36, the method furthercomprising roughening the surface of the second metal layer.
 47. Themethod for producing a transfer material according to claim 46, whereinan average central line roughness of the roughened surface of the secondmetal layer is 2 μm or more.
 48. The method for producing a transfermaterial according to claim 36, wherein a circuit component is formed bya printing method so that it is in contact with the second metal layer.49. The method for producing a transfer material according to claim 48,wherein the printing method is a screen printing method.
 50. The methodfor producing a transfer material according to claim 48, wherein thecircuit component is formed of a material comprising an inorganic fillerand a resin composition.
 51. The method for producing a transfermaterial according to claim 48, wherein the circuit component is formedof a material comprising an inorganic filler, an organic binder and aplasticizer.
 52. A method for producing a transfer material, comprisingforming a second metal layer into a wiring pattern on the first metallayer, and forming a circuit component by a printing method forelectrically connecting to the second metal layer.
 53. The method forproducing a transfer material according to claim 52, wherein the circuitcomponent is formed by a screen printing method.
 54. The method forproducing a transfer material according to claim 52, wherein the secondmetal layer is formed by plating.
 55. A method for producing a transfermaterial, comprising forming a peel layer and a second metal layer on afirst metal layer, processing the second metal layer and the peel layerinto a wiring pattern, and forming a circuit component by a printingmethod for electrically connecting to the second metal layer.
 56. Themethod for producing a transfer material according to claim 55, whereinthe circuit component is formed by a screen printing method.
 57. Themethod for producing a transfer material according to claim 55, whereinthe second metal layer and the peel layer are processed into the wiringpattern by a chemical etching process and at the same time, the convexand concave portion having a convex portion corresponding to the wiringpattern on the surface portion of the first metal layer.
 58. The methodfor producing a transfer material according to claim 57, the methodcomprising, after the second metal layer is formed and before theetching is carried out, (a) forming a plating resist on the second metallayer with the surface portion of the second metal layer exposed in thewiring pattern, (b) forming a third metal layer by plating in a regionwhere the second metal layer is exposed, and (c) peeling off the platingresist; thereafter, etching the second metal layer, the peel layer, andthe surface portion of the first metal layer in a region where the thirdmetal layer is not formed by a chemical etching process.
 59. The methodfor producing a transfer material according to claim 58, wherein thethird metal layer is formed of a metal component chemically stable withrespect to an etchant used for the chemical etching process, and thethird metal layer is allowed to serve as an etching resist in thechemical etching process.
 60. The method for producing a transfermaterial according to claim 59, wherein the third metal layer is formedof gold or silver.
 61. The method for producing a transfer materialaccording to claim 58, the method comprising, after the third metallayer is formed and before the plating resist is peeled off, forming afourth metal layer on the third metal layer by the use of a metalcomponent chemically stable with respect to an etchant used for thechemical etching process, and thereafter, peeling off the platingresist, and etching the second metal layer, the peeling layer and thesurface portion of the first metal layer in a region where the third andfourth metal layers are not formed by a chemical etching process. 62.The method for producing a transfer material according to claim 61,wherein the fourth metal layer is formed of a metal component chemicallystable with respect to the etchant used for the chemical etching processand, the fourth metal layer is allowed to serve as an etching resist inthe chemical etching process.
 63. The method for producing a transfermaterial according to claim 62, wherein the fourth metal layer is formedof gold or silver.
 64. The method for producing a transfer materialaccording to claim 57, wherein the second metal layer is formed byelectrolytic plating.
 65. The method for producing a transfer materialaccording to claim 57, wherein the first metal layer and the secondmetal layer are formed of the same metal component.
 66. The method forproducing a transfer material according to claim 57, wherein a depth ofthe surface portion of the first metal layer that is etched by thechemical etching process is 1 to 12 μm.
 67. The method for producing atransfer material according to claim 57, the method further comprisingroughening the surface of the second metal layer.
 68. The method forproducing a transfer material according to claim 67, wherein an averagecentral line roughness of the roughened surface of the second metallayer is 2 μm or more.
 69. A wiring substrate comprising an electricinsulating substrate, and a wiring pattern formed on at least oneprincipal plane of the electric insulating substrate by a transfermethod by the use of the transfer material according to claim 1, whereinthe wiring pattern is formed in the concave portion formed on theprincipal plane.
 70. The wiring substrate according to claim 69, whereinthe electric insulating substrate is provided with a through hole filledwith a conductive composition, and the wiring pattern is electricallyconnected to the conductive composition.
 71. The wiring substrateaccording to claim 69, wherein a depth of the concave portion is 1 to 12μm.
 72. The wiring substrate according to claim 69, wherein the electricinsulating substrate comprises an inorganic filler and a thermosettingresin, and has a through hole filled with a conductive composition. 73.The wiring substrate according to claim 72, wherein the inorganic fillercomprises at least one inorganic filler selected from the groupconsisting of Al₂O₃, MgO, BN, AlN and SiO₂, the content of the inorganicfiller is 70 to 95 weight %, and the content of the thermosetting resincomposition is 5 to 30 weight %.
 74. The wiring substrate according toclaim 69, wherein the electric insulating substrate is a reinforcerimpregnated with a thermosetting resin, and the reinforcer is at leastone selected from the group consisting of a woven fabric of a glassfiber, a non-woven fabric of a glass fiber, a woven fabric of a thermalresistant organic fiber and a non-woven fabric of a thermal resistantorganic fiber.
 75. The wiring substrate according to claim 69, whereinthe electric insulating substrate is formed of a ceramic.
 76. The wiringsubstrate according to claim 75, wherein the ceramic comprises at leastone component selected from the group consisting of Al₂O₃, MgO, ZrO₂,TiO₂, SiO₂, BeO, BN, CaO and glass, or a Bi—Ca—Nb—O containing ceramic.77. The wiring substrate according to claim 69, further comprising ametal layer formed by plating on the wiring pattern that is formed by atransfer method in the concave portion on the principal plane.
 78. Thewiring substrate according to claim 69, comprising a semiconductordevice connected to the wiring pattern formed in the concave portion onthe principal plane, the semiconductor device being flip-chip bonded onthe wiring pattern by positioning the bump of the semiconductor devicein the concave portion.
 79. A multi-layered wiring substrate having aninner via hole structure in which a plurality of wiring substrates arelaminated, wherein at least one layer has a wiring substrate accordingto claim
 69. 80. The wiring substrate according to claim 79, wherein atleast one of the plurality of wiring substrates is a ceramic wiringsubstrate having an electric insulating substrate including a ceramic,at least one of the ceramic wiring substrates has a convex wiringpattern formed on at least one principal plane, the wiring substratelaminated on the principal plane having the convex wiring pattern is acomposite wiring substrate having an electric insulating substrateincluding a thermosetting resin composition, and the convex wiringpattern is embedded in the principal plane of the composite wiringsubstrate.
 81. The wiring substrate according to claim 80, wherein thesintering temperature of the ceramic wiring substrate is 1050° C. orhigher.
 82. The wiring substrate according to claim 79, wherein at leasttwo of the plurality of wiring substrates are ceramic wiring substrateshaving an electric insulating substrate including a ceramic, at leastone of the ceramic wiring substrates comprises a ceramic materialdifferent from the ceramic material of the other ceramic wiringsubstrates, and a wiring substrate having an electric insulatingsubstrate including a thermosetting resin composition is placed betweenthe ceramic wiring substrates each containing a different ceramicmaterial.
 83. The wiring substrate according to claim 79, wherein atleast a top layer and a bottom layer of the plurality of wiringsubstrates are composite substrates having an electric insulatingsubstrate including a thermosetting resin composition, and an insidelayer is a ceramic wiring substrate having an electric insulatingsubstrate including a ceramic.
 84. A wiring substrate, comprising anelectric insulating substrate, and a wiring pattern and a circuitcomponent that are formed on at least one principal plane of theelectric insulating substrate by a transfer method by the use of thetransfer material according to claim 22, wherein the circuit componentis electrically connected to the wiring pattern, and the circuitcomponent and the wiring pattern are embedded in the principal plane.85. The wiring substrate according to claim 84, wherein the electricinsulating substrate is provided with a through hole filled with aconductive composition, and the wiring pattern is electrically connectedto the conductive composition.
 86. The wiring substrate according toclaim 84, wherein the electric insulating substrate comprises aninorganic filler and a thermosetting resin, and has a through holefilled with a conductive composition.
 87. The wiring substrate accordingto claim 86, wherein the inorganic filler comprises at least oneinorganic filler selected from the group consisting of Al₂O₃, MgO, BN,AlN and SiO₂, the content of the inorganic filler is 70 to 95 weight %,and the content of the thermosetting resin composition is 5 to 30 weight%.
 88. The wiring substrate according to claim 84, wherein the electricinsulating substrate is a reinforcer impregnated with a thermosettingresin, and the reinforcer is at least one selected from the groupconsisting of a woven fabric of a glass fiber, a non-woven fabric of aglass fiber, a woven fabric of a thermal resistant organic fiber and anon-woven fabric of a thermal resistant organic fiber.
 89. The wiringsubstrate according to claim 84, wherein the electric insulatingsubstrate is formed of a ceramic material.
 90. The wiring substrateaccording to claim 89, wherein the ceramic material comprises at leastone component selected from the group consisting of Al₂O₃, MgO, ZrO₂,TiO₂, SiO₂, BeO, BN, CaO and glass, or a Bi—Ca—Nb—O containing ceramic.91. A multi-layered wiring substrate having an inner via hole structurein which a plurality of wiring substrates are laminated, wherein atleast one layer has a wiring substrate according to claim
 84. 92. Thewiring substrate according to claim 91, wherein at least one of theplurality of wiring substrates is a ceramic wiring substrate having anelectric insulating substrate including a ceramic, at least one of theceramic wiring substrates has a convex wiring pattern formed on at leastone principal plane, the wiring substrate laminated on the principalplane having the convex wiring pattern is a composite wiring substratehaving an electric insulating substrate including a thermosetting resincomposition, and the convex wiring pattern is embedded in the principalplane of the composite wiring substrate.
 93. The wiring substrateaccording to claim 92, wherein the sintering temperature of the ceramicwiring substrate is 1050° C. or higher.
 94. The wiring substrateaccording to claim 91, wherein at least two of the plurality of wiringsubstrates are ceramic wiring substrates having an electric insulatingsubstrate including a ceramic, at least one of the ceramic wiringsubstrates comprises a ceramic material different from the ceramicmaterial of the other ceramic wiring substrates, and a wiring substratehaving an electric insulating substrate including a thermosetting resincomposition is placed between the ceramic wiring substrates eachcontaining a different ceramic material.
 95. The wiring substrateaccording to claim 91, wherein at least a top layer and a bottom layerof the plurality of wiring substrates are composite substrates having anelectric insulating substrate including a thermosetting resincomposition, and an inside layer is a ceramic wiring substrate having anelectric insulating substrate including a ceramic.
 96. A method forproducing a wiring substrate using the transfer material according toclaim 1, the method comprising pressing the side of the transfermaterial where the wiring pattern metal layer including at least asecond metal layer is formed onto at least one principal plane of anuncured base material sheet, and peeling off a first metal layer adheredto the second metal layer from the second metal layer, therebytransferring the wiring pattern metal layer to the base material sheet.97. The method for producing a wiring substrate according to claim 96,wherein two or more of the uncured base material sheets to which thewiring pattern metal layer is transferred are laminated so as to form alaminate, and all of the base material sheets of the laminate are curedat one time.
 98. The method for producing a wiring substrate accordingto claim 96, wherein the base material sheet comprises an inorganicfiller and a thermosetting resin composition, and has a through holefilled with the conductive composition.
 99. The method for producing awiring substrate according to claim 98, wherein the inorganic fillercomprises at least one inorganic filler selected from the groupconsisting of Al₂O₃, MgO, BN, AlN and SiO₂, the content of the inorganicfiller is 70 to 95 weight % with respect to an entire base materialsheet, and the content of the thermosetting resin composition is 5 to 30weight % with respect to an entire base material sheet.
 100. The methodfor producing a wiring substrate according to claim 96, wherein the basematerial sheet is a reinforcer impregnated with a thermosetting resin,and the reinforcer is one selected from the group consisting of a wovenfabric of a glass fiber, a non-woven fabric of a glass fiber, a wovenfabric of a thermal resistant organic fiber and a non-woven fabric of athermal resistant organic fiber.
 101. The method for producing a wiringsubstrate according to claim 96, wherein the base material sheetcomprises a polyimide.
 102. The method for producing a wiring substrateaccording to claim 96, wherein the base material sheet is a ceramicsheet comprising an organic binder, a plasticizer and a ceramic powdercomprising at least one ceramic selected from the group consisting ofAl₂O₃, MgO, ZrO₂, TiO₂, SiO₂, BeO, BN, CaO and glass.
 103. The methodfor producing a wiring substrate according to claim 102, comprising,transferring the wiring pattern metal layer to both principal planes ofthe ceramic sheet by using the transfer material, placing a constrainedsheet on both surfaces or one surface of the ceramic sheet, theconstrained sheet having, as a main component, an inorganic compositionthat substantially is not sintered nor shrunk at the firing temperatureof the ceramic sheet, firing the ceramic sheet together with theconstrained sheet, and after firing, removing the constrained sheet soas to form a ceramic wiring substrate.
 104. The method for producing awiring substrate according to claim 103, comprising, transferring thewiring pattern metal layer by the use of the transfer material to atleast one principal plane of the base material sheet including athermosetting resin composition, thereby forming a composite wiringsubstrate, and laminating the ceramic wiring substrate and the compositewiring substrate, and heating and pressing the laminate so as to form amulti-layered wiring substrate.
 105. The method for producing a wiringsubstrate according to claim 103, wherein the ceramic sheet is providedwith a through hole before the wiring pattern metal layer is transferredto the ceramic sheet by the use of the transfer material, and thethrough hole is filled with a conductive composition.
 106. A method forproducing a wiring substrate, comprising providing a ceramic sheet witha through hole, placing a constrained sheet, having an inorganiccomposition that substantially is not sintered nor shrunk at the firingtemperature of the ceramic sheet as a main component, on both surfacesof the ceramic sheet provided with a through hole, firing the ceramicsheet together with the constrained sheet, after firing, removing theconstrained sheet, filling the through hole with a thermosettingconductive composition so as to form a ceramic substrate having a viaconductor, pressing the side where the wiring pattern metal layerincluding at least a second metal layer is formed of the transfermaterial according to claim 1 onto at least one principal plane of anuncured base material sheet including a thermosetting resin composition,peeling off the first metal layer adhered to the second metal layer viathe peel layer from the second metal layer, thereby transferring thewiring pattern metal layer to the base material sheet, providing a basematerial sheet including the thermosetting resin composition with athrough hole before or after the transfer, and filling the through holewith a conductive composition so as to form a composite wiring substratehaving a via conductor, and laminating the ceramic substrate and thecomposite wiring substrate, and heating and pressing the laminate so asto form a multi-layered wiring substrate.
 107. The method for producinga wiring substrate according to claim 106, wherein a through hole for apin for positioning the ceramic substrate with respect to the compositewiring substrate is formed at the same time the ceramic sheet isprovided with a through hole.
 108. The method for producing a wiringsubstrate according to claim 107, wherein a hole diameter of the throughhole is made larger by 2 to 10% than the hole diameter of the pin. 109.The method for producing a wiring substrate according to claim 96,wherein the wiring pattern metal layer is transferred by the use of thetransfer material, and thereafter the wiring pattern metal layer formedon the surface of the base material sheet is plated.
 110. A method forproducing a wiring substrate using the transfer material according claim22, the method comprising pressing the side of the transfer materialwhere the wiring pattern metal layer including at least a second metallayer is formed onto at least one principal plane of an uncured basematerial sheet, and peeling off the first metal layer, therebytransferring at least the second metal layer and the circuit componentto the base material sheet.
 111. The method for producing a wiringsubstrate according to claim 110, wherein two or more of the uncuredbase material sheets after transfer are laminated so as to form alaminate, and all of the base material sheets of the laminate are curedin one time.
 112. The method for producing a wiring substrate accordingto claim 110, wherein the base material sheet comprises an inorganicfiller and a thermosetting resin composition, and has a through holefilled with the conductive composition.
 113. The method for producing awiring substrate according to claim 112, wherein the inorganic fillercomprises at least one inorganic filler selected from the groupconsisting of Al₂O₃, MgO, BN, AlN and SiO₂, the content of the inorganicfiller is 70 to 95 weight % with respect to an entire base materialsheet, and the content of the thermosetting resin composition is 5 to 30weight % with respect to an entire base material sheet.
 114. The methodfor producing a wiring substrate according to claim 110, wherein thebase material sheet is a reinforcer impregnated with a thermosettingresin, and the reinforcer is one selected from the group consisting of awoven fabric of a glass fiber, a non-woven fabric of a glass fiber, awoven fabric of a thermal resistant organic fiber and a non-woven fabricof a thermal resistant organic fiber.
 115. The method for producing awiring substrate according to claim 110, wherein the base material sheetcomprises a polyimide.
 116. The method for producing a wiring substrateaccording to claim 110, wherein the base material sheet is a ceramicsheet comprising an organic binder, a plasticizer and a ceramic powdercomprising at least one ceramic selected from the group consisting ofAl₂O₃, MgO, ZrO₂, TiO₂, SiO₂, BeO, BN, CaO and glass.
 117. The methodfor producing a wiring substrate according to claim 116, comprisingtransferring the wiring pattern metal layer to both principal planes ofthe ceramic sheet by using the transfer material, placing a constrainedsheet on both surfaces or one surface of the ceramic sheet, theconstrained sheet having, as a main component, an inorganic compositionthat substantially is not sintered nor shrunk at the firing temperatureof the ceramic sheet, firing the ceramic sheet together with theconstrained sheet, and after firing, removing the constrained sheet soas to form a ceramic wiring substrate.
 118. The method for producing awiring substrate according to claim 117, comprising, transferring thewiring pattern metal layer by the use of the transfer material to atleast one principal plane of the base material sheet including athermosetting resin composition, thereby forming a composite wiringsubstrate, and laminating the ceramic wiring substrate and the compositewiring substrate, and heating and pressing the laminate so as to form amulti-layered wiring substrate.
 119. The method for producing a wiringsubstrate according to claim 117, wherein the ceramic sheet is providedwith a through hole before the wiring pattern metal layer is transferredto the ceramic sheet by the use of the transfer material, and thethrough hole is filled with a conductive composition.
 120. A method forproducing a wiring substrate, comprising providing a ceramic sheet witha through hole, placing a constrained sheet, having an inorganiccomposition that substantially is not sintered nor shrunk at the firingtemperature of the ceramic sheet as a main component, on both surfacesof the ceramic sheet provided with a through hole, firing the ceramicsheet together with the constrained sheet, after firing, removing theconstrained sheet, filling the through hole with a thermosettingconductive composition so as to form a ceramic substrate having a viaconductor, pressing the side where the wiring pattern metal layerincluding at least a second metal layer is formed of the transfermaterial according to claim 22 onto at least one principal plane of anuncured base material sheet including a thermosetting resin composition,peeling off the first metal layer adhered to the second metal layer viathe peel layer from the second metal layer, thereby transferring thewiring pattern metal layer to the base material sheet, providing a basematerial sheet including the thermosetting resin composition with athrough holes before or after the transfer, and filling the through holewith a conductive composition so as to form a composite wiring substratehaving a via conductor, and laminating the ceramic substrate and thecomposite wiring substrate, and heating and pressing the laminate so asto form a multi-layered wiring substrate.
 121. The method for producinga wiring substrate according to claim 119, wherein a through hole for apin for positioning the ceramic substrate with respect to the compositewiring substrate is formed at the same time the ceramic sheet isprovided with a through hole.
 122. The method for producing a wiringsubstrate according to claim 121, wherein a hole diameter of the throughhole is made larger by 2 to 10% than the hole diameter of the pin. 123.The method for producing a wiring substrate according to claim 110,wherein the wiring pattern metal layer is transferred by the use of thetransfer material, and thereafter the wiring pattern metal layer formedon the surface of the base material sheet is plated.